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Purpose: Menstruation and menstrual symptoms are commonly cited barriers to physical activity in women. The delay or avoidance of menstruation through extended oral-contraceptive (OC) regimens may mitigate these barriers, yet information on menstrual-manipulation practices in young physically active women is sparse. The objective of this study was to investigate prevalence of, and reasons for, menstrual manipulation with OCs in recreationally and competitively active women., Methods: One hundred ninety-one recreationally active (self-reported moderate to vigorous physical activity 150-300 min/wk) women (age 23 ± 5 y), 160 subelite recreationally active (self-reported moderate to vigorous physical activity >300 min/wk) women (age 23 ± 5 y), and 108 competitive (state-, national- or international-level) female athletes (age 23 ± 4 y) completed a self-administered questionnaire assessing OC-regimen habits and reasons for manipulation of menstruation., Results: The majority (74%) of OC users reported having deliberately manipulated menstruation at least once during the previous year, with 29% reporting having done so at least 4 times. Prevalence of menstrual manipulation (at least once in the previous year) was not different between competitive athletes, subelite recreationally active women, and recreationally active women (77% vs 74% vs 72%; P > .05). The most cited reasons for manipulating menstruation were special events or holidays (rated by 75% as important/very important), convenience (54%), and sport competition (54%)., Conclusions: Menstrual manipulation through extended OC regimens is common practice in recreationally and competitively active young women, for a range of reasons relating to convenience that are not limited to physical activity. This strategy may help reduce hormone-related barriers to exercise participation, thereby positively affecting participation and performance.

Postexercise nutrition is a critical component of an athlete's recovery from training and competition. However, little is known about athletes' postexercise dietary practices or knowledge of dietary recommendations, particularly among masters athletes. The purpose of this study was to compare and contrast the knowledge of postexercise nutritional recommendations, and typical postexercise intakes of carbohydrate and protein, between masters and younger triathletes. 182 triathletes (Male = 101, Female = 81) completed an online survey distributed by Triathlon Australia. Knowledge of postexercise nutrition recommendations for protein and carbohydrate intake were assessed as a group, and contrasted between subgroups of masters (≥50 years) and younger triathletes (≤30 years). Using dietary recall, postexercise intakes of carbohydrate and protein were examined and contrasted between masters and younger triathletes. As a group, 43.1% and 43.9% of all triathletes answered, "I don't know" when asked to identify the recommended postexercise carbohydrate and protein intakes, respectively. Dietary analysis revealed masters triathletes consumed significantly less carbohydrate (0.7 ± 0.4 g.kg-1) postexercise than recommended (1.0 g.kg-1; p = .001), and in comparison with younger triathletes (1.1 ± 0.6 g.kg-1; p = .01). Postexercise protein intakes were similar between masters (19.6 ± 13.5 g) and younger (26.4 ± 15.8 g) triathletes. However, relative to body mass, masters triathletes consumed significantly less protein (0.3 ± 0.2 g.kg-1) than younger triathletes (0.4 ± 0.2 g.kg-1; p = .03), and consumed significantly less energy postexercise (22.7 ± 11.7 kJ.kg-1) than younger triathletes (37.8 ± 19.2 kJ.kg-1; p = .01). The present data suggests triathletes have poor knowledge of recommendations for postexercise carbohydrate and protein intakes. Furthermore, low postexercise intakes of carbohydrate and protein by masters athletes may impair acute recovery.

Purpose: Following colorectal cancer diagnosis and anti-cancer therapy, declines in cardiorespiratory fitness and body composition lead to significant increases in morbidity and mortality. There is increasing interest within the field of exercise oncology surrounding potential strategies to remediate these adverse outcomes. This study compared 4 weeks of moderate-intensity exercise (MIE) and high-intensity exercise (HIE) training on peak oxygen consumption (V̇O2peak) and body composition in colorectal cancer survivors., Methods: Forty seven post-treatment colorectal cancer survivors (HIE = 27 months post-treatment; MIE = 38 months post-treatment) were randomised to either HIE [85-95 % peak heart rate (HRpeak)] or MIE (70 % HRpeak) in equivalence with current physical activity guidelines and completed 12 training sessions over 4 weeks., Results: HIE was superior to MIE in improving absolute (p = 0.016) and relative (p = 0.021) V̇O2peak. Absolute (+0.28 L.min(-1), p < 0.001) and relative (+3.5 ml.kg(-1).min(-1), p < 0.001) V̇O2 peak were increased in the HIE group but not the MIE group following training. HIE led to significant increases in lean mass (+0.72 kg, p = 0.002) and decreases in fat mass (-0.74 kg, p < 0.001) and fat percentage (-1.0 %, p < 0.001), whereas no changes were observed for the MIE group. There were no severe adverse events., Conclusions: In response to short-term training, HIE is a safe, feasible and efficacious intervention that offers clinically meaningful improvements in cardiorespiratory fitness and body composition for colorectal cancer survivors., Implications for Cancer Survivors: HIE appears to offer superior improvements in cardiorespiratory fitness and body composition in comparison to current physical activity recommendations for colorectal cancer survivors and therefore may be an effective clinical utility following treatment.

Exercise and physical activity have been shown to reduce the risk of many common cancers and strongly influence tumor biology. A cause-effect mechanism explaining this relationship is dependent on cellular pathways that can influence tumor growth and are exercise responsive. The insulin-like growth factor (IGF) axis is reported to promote the development and progression of carcinomas through cellular signaling in cancerous tissues. This review summarizes the physiologic basis of the role of the IGF axis in oncology and the influence of exercise on this process. We examined the effects of exercise prescription on the IGF axis in cancer survivors by evaluating the current scope of the literature. The current research demonstrates a remarkable heterogeneity and inconsistency in the responses of the IGF axis to exercise in breast, prostate, and colorectal cancer survivors. Finally, this review presents an in-depth exploration of the physiologic basis and mechanistic underpinnings of the seemingly disparate relationship between exercise and the IGF axis in oncology. Although there is currently insufficient evidence to categorize the effects of exercise prescription on the IGF axis in cancer survivors, the inconsistency of results suggests a multifaceted relationship, the complexities of which are considered in this review., (©2015 American Association for Cancer Research.)

Some athletes avoid dairy in the meal consumed before exercise due to fears about gastrointestinal discomfort. Regular exclusion of dairy foods may unnecessarily reduce intake of high quality proteins and calcium with possible implications for body composition and bone health. This study compared the effects of meals that included (Dairy) or excluded (Control) dairy foods on gastric comfort and subsequent cycling performance. Well-trained female cyclists (n = 32; mean ± SD; 24.3 ± 4.1 y; VO(2peak) 57.1 ± 4.9 ml/kg/min) completed two trials (randomized cross-over design) in which they consumed a meal (2 g/kg carbohydrate and 54 kJ/kg) 2 hr before a 90-min cycle session (80 min at 60% maximal aerobic power followed by a 10-min time trial; TT). The dairy meal contained 3 servings of dairy foods providing ~1350 mg calcium. Gut comfort and palatability were measured using questionnaires. Performance was measured as maximum mean power during the TT (MMP10(min)). There was no statistical or clinical evidence of an effect of meal type on MMP10(min) with a mean difference (Dairy - Control) of 4 W (95% CI [-2, 9]). There was no evidence of an association between pretrial gut comfort and meal type (p = .15) or between gut comfort delta scores and meal type postmeal (p = .31), preexercise (p = .17) or postexercise (p = .80). There was no statistical or clinical evidence of a difference in palatability between meal types. In summary, substantial amounts of dairy foods can be included in meals consumed before strenuous cycling without impairing either gut comfort or performance.

Objectives: The purpose of the present study was to examine a possible dose-response between pre-exercise pseudoephedrine intake and cycling time trial performance., Design: Randomised, double-blind, crossover trial., Methods: Ten trained male endurance cyclists (26.5 ± 6.2 years, 75.1 ± 5.9 kg, 70.6 ± 6.8 mL kg(-1)min(-1)) undertook three cycling time trials in which a fixed amount of work (7 kJ kg(-1) body mass) was completed in the shortest possible time. Sixty minutes before the start of exercise, subjects orally ingested either 2.3 mg kg(-1) or 2.8 mg kg(-1) body mass of pseudoephedrine or a placebo in a randomised and double-blind manner. Venous blood was sampled at baseline, pre- and post-warm up and post-exercise for the analysis of pH and lactate and glucose concentrations; plasma catecholamine and pseudoephedrine concentrations were measured at all times except post-warm up., Results: Cycling time trial performance (∼ 30 min) was not enhanced by pseudoephedrine ingestion. Plasma pseudoephedrine concentration increased from pre-warm up to post-exercise in both treatment conditions, with the 2.8 mg kg(-1) body mass dose producing the highest concentration at both time points (2.8 mg kg(-1)>2.3 mg kg(-1)>placebo; p<0.001)., Conclusions: There was large individual variation in plasma pseudoephedrine concentration between subjects following pseudoephedrine administration. A number of factors clearly influence the uptake and appearance of pseudoephedrine in the blood and these are not yet fully understood. Combined with subsequent differences in plasma pseudoephedrine between individuals, this may partially explain the present findings and also the inconsistencies in performance following pseudoephedrine administration in previous studies., (Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

At least 30 minutes of moderate-intensity physical activity accumulated on most, preferably all days is considered the minimum level necessary to reduce the risk of developing cardiovascular disease. Despite an unclear explanation, some epidemiological data paradoxically suggest that a very high volume of exercise is associated with a decrease in cardiovascular health. Although ultra-endurance exercise training has been shown to increase antioxidant defences (and therefore confer a protective effect against oxidative stress), an increase in oxidative stress may contribute to the development of atherosclerosis via oxidative modification of low-density lipoprotein (LDL). Research has also shown that ultra-endurance exercise is associated with acute cardiac dysfunction and injury, and these may also be related to an increase in free radical production. Longitudinal studies are needed to assess whether antioxidant defences are adequate to prevent LDL oxidation that may occur as a result of increased free radical production during very high volumes of exercise. In addition, this work will assist in understanding the accrued effect of repeated ultra-endurance exercise-induced myocardial damage.

The power output achieved at peak oxygen consumption (VO2peak) and the time this power can be maintained (i.e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the VO2 response to exercise at the cycling power that output well trained cyclists achieve their VO2peak (i.e., Pmax). Following a progressive exercise test to determine VO2peak, 43 well trained male cyclists (M age = 25 years, SD = 6; M mass = 75 kg, SD = 7; M VO2peak = 64.8 ml x kg(-1) x min(-1), SD = 5.2) performed two Tmax tests 1 week apart. Values expressed for each participant are means and standard deviations of these two tests. Participants achieved a mean VO2peak during the Tmax test after 176 s (SD = 40; M = 74% of Tmax, SD = 12) and maintained it for 66 s (SD = 39; M = 26% of Tmax, SD = 12). Additionally, they obtained mean 95% of VO2peak after 147 s (SD = 31; M = 62% of Tmax, SD = 8) and maintained it for 95 s (SD = 38; M = 38% of Tmax, SD = 8). These results suggest that 60-70% of Tmax is an appropriate exercise duration for a population of well trained cyclists to attain VO2peak during exercise at Pmax. However, due to intraparticipant variability in the temporal aspects of the VO2 response to exercise at Pmax, future research is needed to examine whether individual high-intensity interval training programs for well trained endurance athletes might best be prescribed according to an athlete's individual VO2 response to exercise at Pmax.

The aim of this study was to compare the cycling performance of cyclists and triathletes. Each week for 3 weeks, and on different days, 25 highly trained male cyclists and 18 highly trained male triathletes performed: (1) an incremental exercise test on a cycle ergometer for the determination of peak oxygen consumption (VO2peak), peak power output and the first and second ventilatory thresholds, followed 15 min later by a sprint to volitional fatigue at 150% of peak power output; (2) a cycle to exhaustion test at the VO2peak power output; and (3) a 40-km cycle time-trial. There were no differences in VO2peak, peak power output, time to volitional fatigue at 150% of peak power output or time to exhaustion at VO2peak power output between the two groups. However, the cyclists had a significantly faster time to complete the 40-km time-trial (56:18 +/- 2:31 min:s; mean +/- s) than the triathletes (58:57 +/- 3:06 min:s; P < 0.01), which could be partially explained (r = 0.34-0.51; P < 0.05) by a significantly higher first (3.32 +/- 0.36 vs 3.08 +/- 0.36 l x min(-1)) and second ventilatory threshold (4.05 +/- 0.36 vs 3.81 +/- 0.29 l x min(-1); both P < 0.05) in the cyclists compared with the triathletes. In conclusion, cyclists may be able to perform better than triathletes in cycling time-trial events because they have higher first and second ventilatory thresholds.

This study examined the effects of four high-intensity interval-training (HIT) sessions performed over 2 weeks on peak volume of oxygen uptake (VO2peak), the first and second ventilatory thresholds (VT1, VT2) and peak power output (PPO) in highly trained cyclists. Fourteen highly trained male cyclists (VO2peak = 67.5 +/- 3.7 ml.kg-1.min-1) performed a ramped cycle test to determine VO2peak, VT1, VT2, and PPO. Subjects were divided equally into a HIT group and a control group. The HIT group performed four HIT sessions (20 x 60 s at PPO, 120 s recovery); the VO2peak test was repeated < 1 wk after the HIT program. Control subjects maintained their regular training program and were reassessed under the same timeline. There was no change in VO2peak for either group; however, the HIT group showed a significantly greater increase in VT1 (+22% vs. -3%), VT2 (+15% vs. -1%), and PPO (+4.3 vs. -.4%) compared to controls (all P < .05). This study has demonstrated that HIT can improve VT1, VT2, and PPO, following only four HIT sessions in already highly trained cyclists.

Fluctuations in estrogen and progesterone during the menstrual cycle can cause changes in body systems other than the reproductive system. For example, progesterone is involved in the regulation of fluid balance in the renal tubules and innervation of the diaphragm via the phrenic nerve. However, few significant changes in the responses of the cardiovascular and respiratory systems, blood lactate, bodyweight, performance and ratings of perceived exertion are evident across the cycle. Nevertheless, substantial evidence exists to suggest that increased progesterone levels during the luteal phase cause increases in both core and skin temperatures and alter the temperature at which sweating begins during exposure to both ambient and hot environments. As heat illness is characterised by a significant increase in body temperature, it is feasible that an additional increase in core temperature during the luteal phase could place females at an increased risk of developing heat illness during this time. In addition, it is often argued that physiological gender differences such as oxygen consumption, percentage body fat and surface area-to-mass ratio place females at a higher risk of heat illness than males. This review examines various physiological responses to heat exposure during the menstrual cycle at rest and during exercise, and considers whether such changes increase the risk of heat illness in female athletes during a particular phase of the menstrual cycle.

Purpose: This study examined the relationships between training workloads, game workloads, and match performance in an elite netball team. Methods: Ten elite female netball athletes were monitored over a complete season. Training and game external workloads were determined through inertial movement units and expressed as absolute PlayerLoad (PL) and change of direction (COD). Monthly workload and training efficiency index were also calculated, which used internal workloads (session rating of perceived exertion and summated heart-rate zones). Game performance was assessed through a performance analysis statistic algorithm called NetPoints. To account for the influence of team game workloads on each other, the average workload for midcourt positions (avgMC) was calculated for each game. Data for each athlete were transformed into z scores, and linear mixed modeling was used to build models to examine the relationships between workloads and game performance. Results: Monthly PL, training efficiency index PL, and avgMC PL were statistically significant (P <.05) and positively related to game PL (z = 0.20–0.35, P <.001–.02). For game COD, statistically significant positive relationships were found between monthly COD (z = 0.29 [0.11], P =.01) and avgMC COD (z = 0.21 [0.09], P =.03). The models for NetPoints found significant negative relationships with monthly PL (z = 0.46 [0.12], P <.001) and COD (z = −0.36 [0.11], P =.01). Conclusions: Higher monthly workloads are related to higher game workload; however, they are also related to decreases in match performance. Therefore, netball practitioners should consider that increases to training workload in a 4-week period prior to a game can influence game workloads and performance. [ABSTRACT FROM AUTHOR]

Professional rugby league (RL) football is a contact sport involving repeated collisions and high-intensity efforts; both training and competition involve high energy expenditure. The present review summarizes and critiques the available literature relating the physiological demands of RL to nutritional requirements and considers potential ergogenic supplements that could improve players' physical capacity, health, and recovery during the preparatory and competition phases of a season. Although there may not be enough data to provide RL-specific recommendations, the available data suggest that players may require approximately 6–8 g·kg−1·day−1 carbohydrate, 1.6–2.6 g·kg−1·day−1 protein, and 0.7–2.2 g·kg−1·day−1 fat, provided that the latter also falls within 20–35% of total energy intake. Competition nutrition should maximize glycogen availability by consuming 1–4 g/kg carbohydrate (∼80–320 g) plus 0.25 g/kg (∼20–30 g) protein, 1–4 hr preexercise for 80–120 kg players. Carbohydrate intakes of approximately 80–180 g (1.0–1.5 g/kg) plus 20–67 g protein (0.25–0.55 g/kg) 0–2 hr postexercise will optimize glycogen resynthesis and muscle protein synthesis. Supplements that potentially improve performance, recovery, and adaptation include low to moderate dosages of caffeine (3–6 mg/kg) and ∼300 mg polyphenols consumed ∼1 hr preexercise, creatine monohydrate "loading" (0.3 g·kg−1·day−1) and/or maintenance (3–5 g/day), and beta-alanine (65–80 mg·kg−1·day−1). Future research should quantify energy expenditures in young, professional male RL players before constructing recommendations. [ABSTRACT FROM AUTHOR]

Purpose: To examine relationships between external- and internal-workload variables in an elite female netball team, with consideration of positional differences. Methods: Nine elite female netball athletes had their weekly workloads monitored across their preseason and competition phases of a season. Internal workload was determined using summated heart-rate (HR) zones and session ratings of perceived exertion (sRPE), whereas external workload was determined using inertial movement units and included absolute PlayerLoad (PL), relative PL (PL per minute), accelerations (ACCEL), decelerations (DECEL), jumps, changes of direction (COD), high-intensity events, medium-intensity events, low-intensity events, PL in the forward direction, PL in the sideways direction, and PL in the vertical direction. Relationships between external- and internal-workload variables in the team and relative to playing position were examined. Results: Across the team, the strongest external workloads that correlated with summated HR zones were PL ( r= .65), COD ( r= .64), ACCEL (r= .61), and DECEL ir =.61). The strongest external workloads that correlated with sRPE were COD ( r= .79), followed by jumps (r=.76), ACCEL ( r= .75), and DECEL (r=.75). For all positions, except-goal shooter, the strongest con-elation was between PL and sRPE (r = .88-94). In the goal-shooter position, the strongest correlation was between summated HR zones and DECEL (r = .89). Conclusions: The inertial movement unit-derived external-workload variables are strongly related to common internal-workload variables. In particular, COD and sRPE appear to provide a good monitoring combination of external and internal training loads for elite netball players. [ABSTRACT FROM AUTHOR]

Purpose: To examine relationships among physical performance, workload, and injury risk in professional rugby league players. Methods: Maximal-effort (n = 112) and submaximal (n = 1084) running performances of 45 players were recorded from 1 club over 2 consecutive seasons. Poorer and better submaximal running performance was determined by higher and lower exercise heart rates, respectively. Exponentially weighted moving averages and daily rolling averages were used to assess microtechnology-derived acute and chronic field-based workloads. The associations among within-individual submaximal running performance, workload, and noncontact lower-limb injury were then investigated. Results: The injury risk associated with poorer submaximal performance was "likely" greater than stable (relative risk = 1.8; 90% confidence interval, 0.9–3.7) and better submaximal performance (relative risk = 2.0; 90% confidence interval, 0.9–4.4). Compared with greater submaximal performance, poorer performance was associated with lower chronic workloads (effect size [d] = 0.82 [0.13], large) and higher acute:chronic workload ratios (d = 0.49 [0.14], small). Chronic workload demonstrated a "nearly perfect" positive relationship with maximal-effort running performance (exponentially weighted moving average, R2 =.91 [.15]; rolling average, R2 =.91 [.14]). At acute:chronic workload ratios >1.9, no differences in injury risk were found between rolling average and exponentially weighted moving average methods (relative risk = 1.1; 90% confidence interval, 0.3–3.8; unclear). Conclusions: Reductions in submaximal running performance are related with low chronic workloads, high acute:chronic workload ratios, and increased injury risk. These findings demonstrate that a submaximal running assessment can be used to provide information on physical performance and injury risk in professional rugby league players. [ABSTRACT FROM AUTHOR]

Physical activity is associated with reduced risks of colorectal cancer (CRC) incidence, recurrence and mortality. While these findings are consistent, the mechanism/s underlying this association remain unclear. Growing evidence supports the many ways in which differing characteristics of the gut microbiota can be tumourigenic or protective against CRC. CRC is characterised by significant dysbiosis including reduced short chain fatty acid‐producing bacteria. Recent findings suggest that exercise can modify the gut microbiota, and these changes are inverse to the changes seen with CRC; however, this exercise‐microbiota interaction is currently understudied in CRC. This review summarises parallel areas of research that are rapidly developing: The exercise–gut microbiota research and cancer–gut microbiota research and highlights the salient similarities. Preliminary evidence suggests that these areas are linked, with exercise mediating changes that promote the antitumorigenic characteristics of the gut microbiota. Future mechanistic and population‐specific studies are warranted to confirm the physiological mechanism/s by which exercise changes the gut microbiota, and the influence of the exercise–gut interaction on cancer specific outcomes in CRC. [ABSTRACT FROM AUTHOR]

Following exercise-induced muscle damage (EIMD), masters athletes take longer to recover than younger athletes. The purpose of this study was to determine the effect of higher than recommended postexercise protein feedings on the recovery of knee extensor peak isometric torque (PIT), perceptions of recovery, and cycling time trial (TT) performance following EIMD in masters triathletes. Eight masters triathletes (52 ± 2 y, ...O2max, 51.8 ± 4.2 ml⋅kg-1⋅min-1) completed two trials separated by seven days in a randomized, double-blind, crossover study. Trials consisted of morning PIT testing and a 30-min downhill run followed by an eight-hour recovery. During recovery, a moderate (MPI; 0.3 g⋅kg-1⋅bolus-1) or high (0.6 g⋅kg-1⋅bolus-1) protein intake (HPI) was consumed in three bolus feedings at two hour intervals commencing immediately postexercise. PIT testing and a 7 kJ⋅kg-1 cycling TT were completed postintervention. Perceptions of recovery were assessed pre- and postexercise. The HPI did not significantly improve recovery compared with MPI (p > .05). However, comparison of within-treatment change shows the HPI provided a moderate beneficial effect (d = 0.66), attenuating the loss of afternoon PIT (-3.6%, d = 0.09) compared with the MPI (-8.6%, d = 0.24). The HPI provided a large beneficial effect (d = 0.83), reducing perceived fatigue over the eight-hour recovery (d = 1.25) compared with the MPI (d = 0.22). Despite these effects, cycling performance was unchanged (HPI = 2395 ± 297 s vs. MPI = 2369 ± 278 s; d = 0.09). In conclusion, doubling the recommended postexercise protein intake did not significantly improve recovery in masters athletes; however, HPI provided moderate to large beneficial effects on recovery that may be meaningful following EIMD. [ABSTRACT FROM AUTHOR]

Purpose: To assess the impact of different repeated-high-intensity-effort (RHIE) bouts on player activity profiles, skill involvements, and neuromuscular fatigue during small-sided games, Participants: 22 semiprofessional rugby league players (age 24.0 ± 1.8 y, body mass 95.6 ± 7.4 kg). Methods: During 4 testing sessions, they performed RHIE bouts that each differed in the combination of contact and running efforts, followed by a 5-min off-side small-sided game before performing a second bout of RHIE activity and another 5-min small-sided game. Global positioning system microtechnology and video recordings provided information on activity profiles and skill involvements. A countermovement jump and a plyometric push-up assessed changes in lower- and upper-body neuromuscular function after each session. Results: After running-dominant RHIE bouts, players maintained running intensities during both games. In the contact-dominant RHIE bouts, reductions in moderate-speed activity were observed from game 1 to game 2 (ES = -0.71 to -1.06). There was also moderately lower disposal efficiency across both games after contact-dominant RHIE activity compared with running-dominant activity (ES = 0.62-1.02). Greater reductions in lower-body fatigue occurred as RHIE bouts became more running dominant (ES = -0.01 to-1.36), whereas upper-body fatigue increased as RHIE bouts became more contact dominant (ES - -0.07 to -1.55). Conclusions: Physical contact causes reductions in running intensity and the quality of skill involvements during game-based activities. In addition, the neuromuscular fatigue experienced by players is specific to the activities performed. [ABSTRACT FROM AUTHOR]

Objectives: Recent research has revealed that low volume resistance 'priming' exercise may improve neuromuscular performance when completed within 48h before competition. The aim of this study was to investigate the current prevalence and application of this strategy by practitioners in sport.Design: This study surveyed practitioners who were currently programming and/or prescribing resistance training programs for high performance athletes.Methods: Sixty-nine practitioners completed the online survey relating to their perceptions of resistance priming exercise strategies and the training methods prescribed in the days prior to competition.Results: Fifty-one percent of respondents currently prescribed priming exercise. Of the practitioners who prescribed this strategy, most respondents (59%) prescribed this session within 8h of competition. Sessions typically included 2-3 upper body and lower body exercises (mean=2.5±0.7 and 2.1±0.6 respectively), usually involving both loaded and unloaded activities. Large variations in exercise selection were reported, however, unloaded jumps (87%), loaded jumps (60%) and bench press (56%) were commonly prescribed. A low volume of sets (mean=2.8±0.9) and repetitions (mean=3.8±1.3) were used during these sessions. Lastly, various resistance loading strategies were prescribed, ranging from unloaded activities to heavy loaded exercises performed at ≥85% 1RM.Conclusions: Priming exercise is currently prescribed by many practitioners to prepare athletes for competition. A wide range of priming exercise methods are used, despite limited evidence supporting these methods. Future research should examine the effects of the various priming methods which are currently applied in practice. [ABSTRACT FROM AUTHOR]

The aim of the current study was to investigate the effect of 180 mg of pseudoephedrine (PSE) on cycling time-trial (TT) performance. Six well-trained male cyclists and triathletes (age 33 ± 2 yr, mass 81 ± 8 kg, height 182.0 ± 6.7 cm, VO2max 56.8 ± 6.8 ml · kg-1 · min-1; M ± SD) underwent 2 performance trials in which they completed a 25-min variable-intensity (50-90% maximal aerobic power) warm-up, followed by a cycling TT in which they completed a fixed amount of work (7 kJ/kg body mass) in the shortest possible time. Sixty minutes before the start of exercise, they orally ingested 180 mg of PSE or a cornstarch placebo (PLA) in a randomized, crossover, double-blind manner. Venous blood was sampled immediately pre- and postexercise for the analysis of pH plus lactate, glucose, and norepinephrine (NE). PSE improved cycling TT performance by 5.1% (95% CI 0-10%) compared with PLA (28:58.9 ± 4:26.5 and 30:31.7 ± 4:36.7 min, respectively). There was a significant Treatment × Time interaction (p = .04) for NE, with NE increasing during the PSE trial only. Similarly, blood glucose also showed a trend (p = .06) for increased levels postexercise in the PSE trial. The ingestion of 180 mg of PSE 60 min before the onset of high-intensity exercise improved cycling TT performance in well-trained athletes. It is possible that changes in metabolism or an increase in central nervous system stimulation is responsible for the observed ergogenic effect of PSE. [ABSTRACT FROM AUTHOR]

Key points: Physical activity is associated with reduced mortality rates for survivors of colorectal cancer.Acute high intensity interval exercise (HIIE) reduced colon cancer cell number in vitro and promoted increases in inflammatory cytokines immediately following exercise.This acute suppression of colon cancer cell number was transient and not observed at 120 minutes post-acute HIIE.The acute effects of exercise may constitute an important mechanism by which exercise can influence colorectal cancer outcomes. Physical activity is associated with significant reductions in colorectal cancer mortality. However, the mechanisms by which exercise mediates this anti‐oncogenic effect are not clear. In the present study, colorectal cancer survivors completed acute (n = 10) or chronic (n = 10) exercise regimes. An acute high intensity interval exercise session (HIIE; 4 × 4 min at 85–95% peak heart rate) was completed with serum samples collected at baseline, as well as 0 and 120 min post‐exercise. For the 'chronic' intervention, resting serum was sampled before and after 4 weeks (12 sessions) of HIIE. The effect of serum on colon cancer cell growth was evaluated by incubating cells (CaCo‐2 and LoVo) for up to 72 h and assessing cell number. Serum obtained immediately following HIIE, but not 120 min post‐HIIE, significantly reduced colon cancer cell number. Significant increases in serum interleukin‐6 (P = 0.023), interleukin‐8 (P = 0.036) and tumour necrosis factor‐α (P = 0.003) were found immediately following acute HIIE. At rest, short‐term HIIE training did not promote any changes in cellular growth or cytokine concentrations. The acute effects of HIIE and the cytokine flux may be important mediators of reducing colon cancer cell progression. Repetitive exposure to these acute effects may contribute to the relationship between exercise and improved colorectal cancer survival. Key points: Physical activity is associated with reduced mortality rates for survivors of colorectal cancer.Acute high intensity interval exercise (HIIE) reduced colon cancer cell number in vitro and promoted increases in inflammatory cytokines immediately following exercise.This acute suppression of colon cancer cell number was transient and not observed at 120 minutes post-acute HIIE.The acute effects of exercise may constitute an important mechanism by which exercise can influence colorectal cancer outcomes. [ABSTRACT FROM AUTHOR]

Purpose: Stroke rate (SR) has not been considered in previous research examining the relative roles of the limbs in front-crawl performance. This study compared velocity, aerobic power ([Formula: see text]) and metabolic cost (C) between whole body (WB) and arms only (AO) front-crawl swimming across various intensities while controlling SR.Methods: Twenty Australian national swimmers performed six 200 m front-crawl efforts under two conditions: (1) WB swimming and, (2) AO swimming. Participants completed the 200 m trials under three SR conditions: "low" (22-26 stroke-cycles min(-1)), "moderate" (30-34 stroke-cycles min(-1) and "high" (38-42 stroke-cycles min(-1)). [Formula: see text] was continuously measured, with C, velocity, SR, and kick rate calculated for each effort.Results: Regardless of the SR condition and sex, AO velocity was consistently lower than WB velocity by ~11.0 % (p < 0.01). AO [Formula: see text] was lower than WB [Formula: see text] at all SR conditions for females (p < 0.01) and at the "high" SR for males (p < 0.01). C did not differ between WB and AO at any SR for both sexes (p > 0.01). When C was expressed as a function of velocity, WB and AO regression equations differed for males (p = 0.01) but not for females (p = 0.087). Kick rate increased as SR increased (p < 0.01), though the kick-to-stroke rate ratio remained constant.Conclusion: Elite swimmers gain ~11 % in velocity from their kick and, when used in conjunction with the arm stroke at the swimmers' preferred frequency, the metabolic cost of WB and AO swimming is the same. Coaches should consider these results when prescribing AO sets if their intention is to reduce the metabolic load. [ABSTRACT FROM AUTHOR]

Background: Regular exercise has been recommended as a potential strategy to counteract the age-related bone loss experienced by men; however, the optimal exercise prescription is not known.Objective: To perform a pilot study to examine the osteogenic effect, safety and feasibility of a combined program of upper body resistance exercise and two doses of impact-loading exercise on bone mineral density (BMD) of middle-aged and older men.Methods: Forty-two community-dwelling men aged 50-74 years were randomly assigned to either an exercise program of combined upper body resistance exercise and either high-dose impact-loading (HI; 80 jumps per session) or moderate-dose impact-loading (MOD; 40 jumps per session) or a control (CON) group. The 9-month intervention involved 4 sessions each week: 2 supervised clinic-based and 2 home-based. BMD of the lumbar spine, femoral neck, total hip, trochanter and whole body as well as lean and fat mass were assessed at baseline and 9 months by dual-energy X-ray absorptiometry. Bone turnover markers, hormone levels, physical function and muscle strength were also assessed.Results: Following 9 months of training, significant differences in BMD among groups were found at the total hip (p = 0.010) and trochanter (p = 0.047) with BMD in the MOD group decreasing relative to the HI group. Although not significant, the HI group consistently preserved BMD, whereas BMD of the MOD and CON groups declined at the hip sites. Mean change for all groups at all skeletal sites was approximately within ±1%. There was no change in bone turnover markers. There were no adverse events as a result of the intervention; however, overall attendance for the HI and MOD groups was 53% (clinic: 68%, home: 38%) and 65% (clinic: 74%, home: 55%), respectively.Conclusions: This study indicates that while impact-loading exercise can be safely undertaken in middle-aged and older men, the current combined program did not elicit significant improvements in BMD. [ABSTRACT FROM AUTHOR]

The article discusses research which investigated how three contact efforts influence running performance of athletes during small-sided rugby league games. Topics explored include the recruitment and physical evaluation of study participants, the way repeated high-intensity effort (RHIE) can affect physical performance of athletes, and the statistical analyses of data gathered such as relative distance, low-speed activity, and moderate speed running.

Objectives To determine whether differences in training status, body composition and/or habitual caffeine intake influenced serum caffeine concentrations following caffeine ingestion. Design Single-blind. Methods Trained cyclists/triathletes (n = 14) and active (n = 14) males consumed 6 mg kg-1 anhydrous caffeine. Peak, total and time to peak serum caffeine concentrations were determined from venous blood samples at baseline and 6 time-points over 4 h following intake. Body composition was assessed by dual energy X-ray absorptiometry and habitual caffeine intake by a questionnaire. Results Trained cyclists/triathletes had 16% lower peak caffeine concentrations following caffeine ingestion compared to active individuals, although this was not statistically significant (p = 0.066). There was no significant difference between trained cyclists/triathletes and active males in total (p = 0.131) or time to peak (p = 0.249) serum caffeine concentrations. Fat mass was significantly associated with total (r = 0.427, p = 0.038) but not peak (r = 0.343, p = 0.101) or time to peak serum caffeine concentration (β = 0.00008, p = 0.961). There were no associations between habitual caffeine intake and peak, total or time to peak serum caffeine concentrations. Conclusions Following caffeine ingestion three findings from the study were evident: (1) endurance-trained athletes trended towards lower peak caffeine concentrations compared to active males; (2) higher fat mass was associated with higher concentrations of caffeine in the blood over 4 h, and (3) habitual caffeine intake does not appear to influence serum caffeine concentrations. Identification of the optimal conditions to ensure peak availability of caffeine within the blood and/or overcoming some of the variation in how individuals respond to caffeine requires consideration of the training status and body composition of the athlete. [ABSTRACT FROM AUTHOR]

Physical activity (PA) is related to colorectal cancer (CRC) mortality, with approximately 15% of CRC deaths worldwide attributable to physical inactivity. Moreover, higher levels of PA in CRC survivors have been associated with a reduced risk of the disease recurring. Despite the recognised nexus between PA and the risk of CRC, the physiological mechanisms underlying the inverse relationship between PA and mortality following CRC diagnosis are less apparent, with evidence primarily drawn from epidemiological studies. The insulin-like growth factor (IGF) axis plays a central role in cellular growth, proliferation regulation, differentiation and apoptosis. Specifically, high levels of insulin-like growth factor 1 (IGF-1) have been consistently linked to the severity of CRC tumours. Further, insulin-like growth factor binding protein 3 (IGFBP-3) regulates the bioavailability of IGF-I and therefore plays a central role in CRC prognosis. Decreasing levels of IGF-1 and increasing levels of IGFBP-3 may thus be a plausible mechanism underlying the inverse association between PA and CRC survival. [ABSTRACT FROM AUTHOR]

Objectives: To examine the effect of a high carbohydrate meal on serum caffeine concentration following caffeine intake. Design: Randomised, double-blind, crossover. Methods: Fourteen healthy males randomly completed 4 trials, each separated by 5 days. Participants either remained fasted (on 2 occasions) or ingested a high carbohydrate meal (2.0gkg−1 carbohydrate, 42.4±0.6kJkg−1) prior to consuming either 6 or 9mgkg−1 anhydrous caffeine. Venous blood was sampled for the analysis of serum caffeine at baseline and at 6 time-points over 4h following caffeine intake. Results: Peak caffeine concentration occurred 60min following ingestion for both the 6 and 9mgkg−1 fasted (p <0.001) trials compared to 120 and 180min following ingestion for the 6 and 9mgkg−1 fed trials, respectively (p <0.001). Peak concentration was greater in the 9mgkg−1 fasted trial than the corresponding fed condition (70±9μmolL−1 and 56±6μmolL−1, respectively) and both were greater than the 6mgkg−1 conditions (44±8μmolL−1 and 38±8μmolL−1 for 6mgkg−1 fasted and fed, respectively). Area under the caffeine curve was significantly greater (p <0.001) in the 9mgkg−1 fasted trial (3262μmolL−1 h−1), whilst areas were lowest in the 6mgkg−1 fed trial (1644μmolL−1 h−1). Conclusions: A high carbohydrate meal consumed prior to caffeine ingestion significantly reduced serum caffeine concentrations and delayed time to peak concentration. Differences in research findings between caffeine supplementation studies may, at least in part, be related to variations in postprandial timing of caffeine intake. The influence of postprandial timing should be considered when athletes consume caffeine with the aim of enhancing performance. [ABSTRACT FROM AUTHOR]

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