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Hoffmann, SM, Skinner, TL, van Rosendal, SP, Osborne, MA, Emmerton, LM, and Jenkins, DG. The efficacy of the lactate threshold: A sex-based comparison. J Strength Cond Res 34(11): 3190-3198, 2020-The second lactate threshold (LT2) has previously been associated with endurance performance; however, comparisons between sexes are lacking regarding its efficacy. The aim of this study was to compare LT2 between men and women, specifically regarding its (a) relationship with endurance performance and (b) capacity to establish training and competition intensities. Competitive male (mean ± SD: age, 27.7 ± 4.7 years; V[Combining Dot Above]O2max, 59.7 ± 5.2 ml·kg·min; n = 10) and female (mean ± SD: age, 27.3 ± 6.2 years; V[Combining Dot Above]O2max, 54.5 ± 5.3 ml·kg·min; n = 12) cyclists and triathletes completed an incremental cycle trial to volitional fatigue (for determination of V[Combining Dot Above]O2max and LT2 via the modified D-max method), a constant load (±5%) exercise trial of 30 minutes at LT2 power output, and a 40-km cycle time trial. The LT2 significantly correlated with 40-km cycling performance in both men (r = -0.69 to -0.77; p < 0.01-0.05) and women (r = -0.63 to -0.75; p < 0.01-0.05). All men sustained LT2 power output for 30 minutes, compared with 82% of women. Despite LT2 reflecting a similar heart rate, V[Combining Dot Above]O2, and [La] to those elicited during a 40-km time trial in both men and women, power output at LT2 was 6% higher (p < 0.05) than mean time trial power output in women, with no significant difference in men. Based on these findings, sex-specific recommendations have been suggested in regard to the use of LT2 for establishing performance potential, prescribing endurance training intensities and setting 40-km performance intensity.

The aims of this study were to describe normative values and seasonal variation of body composition in female cyclists comparing female road and track endurance cyclists, and to validate the use of anthropometry to monitor lean mass changes. Anthropometric profiles (seven site skinfolds) were measured over 16 years from 126 female cyclists. Lean mass index (LMI) was calculated as body weight × skinfolds(-x). The exponent (x) was calculated as the slope of the natural logarithm of body weight and skinfolds. Percentage changes in LMI were compared to lean mass changes measured using dual-energy X-ray absorptiometry (DXA) in a subset of 25 road cyclists. Compared to sub-elite and elite cyclists, world class cyclists were (mean [95% CI]) 1.18 kg [0.46, 1.90] and 0.60 kg [0.05, 1.15] lighter and had skinfolds that were 7.4 mm [3.8, 11.0] and 4.6 mm [1.8, 7.4] lower, respectively. Body weight (0.41 kg [0.04, 0.77]) and skinfolds (4.0 mm [2.1, 6.0]) were higher in the off-season compared to the early-season. World class female road cyclists had lower body weight (6.04 kg [2.73, 9.35]) and skinfolds (11.5 mm [1.1, 21.9]) than track endurance cyclists. LMI (mean exponent 0.15 [0.13, 0.18]) explained 87% of the variance in DXA lean mass. In conclusion, higher performing female cyclists were lighter and leaner than their less successful peers, road cyclists were lighter and leaner than track endurance cyclists, and weight and skinfolds were lowest early in the season. LMI appears to be a reasonably valid tool for monitoring lean mass changes.

Purpose: The objective of this study is to compare the integrated muscle protein synthesis (MPS) rates of masters and younger triathletes over three consecutive days of intense endurance training. Recovery of cycling performance, after muscle-damaging running, was also compared between groups., Methods: Five masters (age, 53 ± 2 yr; V˙O2max, 55.7 ± 6.9 mL·kg·min) and six younger (age, 27 ± 2 yr; V˙O2max, 62.3 ± 1.5 mL·kg·min) trained triathletes volunteered for the study. Baseline skeletal muscle and saliva were initially sampled, after which a 150-mL bolus of deuterium oxide (70%) was consumed. Participants then completed a 30-min downhill run; three 20-km cycling time trials (TT) were completed 10, 24, and 48 h after the run. Saliva was collected each morning, and skeletal muscle was again sampled 72 h after the run; both were used for MPS analysis. Diet was controlled throughout the study., Results: Over 3 d, masters triathletes showed a significantly lower myofibrillar fractional synthetic rate (1.49% ± 0.12%·d) compared with the younger (1.70% ± 0.09%·d) triathletes (P = 0.009, d = 1.98). There was also a trend for masters triathletes to produce a slower cycle TT (-3.0%, d = 0.46) than younger triathletes (-1.4%, d = 0.29) at 10 h postrun in comparison with the baseline performance. The between-group comparison of change was moderate (d = 0.51), suggesting slower acute recovery among masters triathletes., Conclusions: The present data show lower MPS rates in well-trained masters triathletes over 3 d of training, and this likely contributes to poorer muscle protein repair and remodeling. Furthermore, acute recovery of cycle TT performance tended to be poorer in the masters triathletes.

Cycling is recognised as a sport in which there is a high incidence of poor bone health. Sweat calcium losses may contribute to this., Purpose: To examine whether a calcium-rich pre-exercise meal attenuates exercise-induced perturbations of bone calcium homeostasis caused by maintenance of sweat calcium losses., Methods: Using a randomized, counterbalanced crossover design, 32 well-trained female cyclists completed two 90 min cycling trials separated by 1 day. Exercise trials were preceded 2 hours by either a calcium-rich (1352 ± 53 mg calcium) dairy based meal (CAL) or a control meal (CON; 46 ± 7 mg calcium). Blood was sampled pre-trial; pre-exercise; and immediately, 40 min, 100 min and 190 min post-exercise. Blood was analysed for ionized calcium and biomarkers of bone resorption (Cross Linked C-Telopeptide of Type I Collagen (CTX-I), Cross Linked C-Telopeptide of Type II Collagen (CTX-II), Parathyroid Hormone (PTH), and bone formation (Procollagen I N-Terminal Propeptide (PINP)) using the established enzyme-linked immunosorbent assay technique., Results: PTH and CTX-I increased from pre-exercise to post-exercise in both conditions but was attenuated in CAL (p < 0.001). PTH was 1.55 [1.20, 2.01] times lower in CAL immediately post-exercise and 1.45 [1.12, 1.88] times lower at 40 min post-exercise. CTX-I was 1.40 [1.15, 1.70] times lower in CAL at immediately post-exercise, 1.30 [1.07, 1.57] times lower at 40 min post-exercise and 1.22 [1.00, 1.48] times lower at 190 min post-exercise (p < 0.05). There was no significant interaction between pre-exercise meal condition and time point for CTX-II (p = 0.732) or PINP (p = 0.819)., Conclusion: This study showed that a calcium-rich pre-exercise breakfast meal containing ~1350 mg of calcium consumed ~90 min before a prolonged and high intensity bout of stationary cycling attenuates the exercise induced rise in markers of bone resorption--PTH and CTX-I., Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN12614000675628.

Purpose: This study investigated the satisfaction of elite female cyclists with their body weight (BW) in the context of race performance, the magnitude of BW manipulation, and the association of these variables with menstrual function., Methods: Female competitors in the Australian National Road Cycling Championships (n = 32) and the Oceania Championships (n = 5) completed a questionnaire to identify current BW, BW fluctuations, perceived ideal BW for performance, frequency of weight consciousness, weight-loss techniques used, and menstrual regularity., Results: All but 1 cyclist reported that female cyclists are "a weight-conscious population," and 54% reported having a desire to change BW at least once weekly; 62% reported that their current BW was not ideal for performance. Their perceived ideal BW was (mean ± SD) 1.6 ± 1.6 kg (2.5% ± 2.5%) less than their current weight (P < .01), and 73% reported that their career-lowest BW was either "beneficial" or "extremely beneficial" for performance. 65% reported successfully reducing BW in the previous 12 months with a mean loss of 2.4 ± 1.0 kg (4.1% ± 1.9%). The most common weight-loss technique was reduced energy intake (76%). Five cyclists (14%) had been previously diagnosed as having an eating disorder by a physician. Of the 18 athletes not using a hormonal contraceptive, 11 reported menstrual dysfunction (oligomenorrhea or amenorrhea)., Conclusion: Elite Australian female cyclists are a weight-conscious population who may not be satisfied with their BW leading into a major competition and in some cases are frequently weight conscious.

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.

Body composition in a female road cyclist was measured using dual-energy X-ray absorptiometry (5 occasions) and anthropometry (10 occasions) at the start of the season (Dec to Mar), during a period of chronic fatigue associated with poor weight management (Jun to Aug), and in the following months of recovery and retraining (Aug to Nov). Dietary manipulation involved a modest reduction in energy availability to 30-40 kcal · kg fat-free mass(-1) · d(-1) and an increased intake of high-quality protein, particularly after training (20 g). Through the retraining period, total body mass decreased (-2.82 kg), lean mass increased (+0.88 kg), and fat mass decreased (-3.47 kg). Hemoglobin mass increased by 58.7 g (8.4%). Maximal aerobic- and anaerobic-power outputs were returned to within 2% of preseason values. The presented case shows that through a subtle energy restriction associated with increased protein intake and sufficient energy intake during training, fat mass can be reduced with simultaneous increases in lean mass, performance gains, and improved health.

Purpose: The objective of this study is to compare the effects of constant- and variable-intensity cycling on gross efficiency (GE) and to compare estimates of energy expenditure (EE) made using indirect calorimetry (CAL) with estimates derived from commercially available power meters., Methods: Nine national team female road cyclists completed a GE test (GEtest = 4 min at approximately 45%, approximately 55%, approximately 65%, and approximately 75% maximal aerobic power (MAP)) before and after 10.5 min of either constant- (CON)- or variable- (VAR)-intensity cycling averaging approximately 55% MAP. GE measured before, after, and during CON and VAR cycling was compared. Total EE (kJ) for 10.5 min of VAR cycling was estimated using indirect CAL and compared with estimates on the basis of mechanical power [Schoberer Rad Messtechnik (SRM)] using the group mean GE, each athlete's mean GE, and each athlete's power to GE regression., Results: There was no effect of VAR on GEtests (P = 0.74). GE reduced from 19.1% ± 0.4% (mean ± SE) during the pretrial GEtests to 18.7% ± 0.4% during the posttrial GEtests (P < 0.05) in both conditions. Differences in GE (mean ± SD) measured during CON (18.4% ± 1.6%) and VAR cycling (18.6% ± 1.1%) were trivial (P = 0.28). SRM-based estimates of EE were most accurate when using individual athlete's power GE regression using Pre- and Post-VAR GEtest data combined (Δ(Equation is included in full-text article.)(%) ± 90% CI, 0.3 ± 0.8; R 0.98, P <0.001). Group mean estimates were within approximately 1% of CAL, although individual errors were approximately 11%., Conclusion: Findings support the use of calibrated power meters for estimating cycling EE. For trained female road cyclists, total mechanical work (kJ) multiplied by 5.3 (GE = 19%) provides a valid estimation of total EE during variable-intensity cycling <75% MAP, although determining each athlete's GE improves accuracy greatly.

Purpose: This study examined the influence of preexercise food intake on plasma pseudoephedrine (PSE) concentrations and subsequent high-intensity exercise. In addition, urinary PSE concentrations were measured under the same conditions and compared with the present threshold of the World Anti-Doping Agency (WADA)., Methods: Ten highly trained male cyclists and triathletes (age = 30.6 ± 6.6 yr, body mass [BM] = 72.9 ± 5.1 kg, and V˙O2max = 64.8 ± 4.5 mL·kg·min; mean ± SD) undertook four cycling time trials (TT), each requiring the completion of a set amount of work (7 kJ·kg BM) in the shortest possible time. Participants were randomized into a fed or nonfed condition and orally ingested 2.8 mg·kg BM of PSE or a placebo (PLA) 90 min before exercise; in the fed trials, they consumed a meal providing 1.5 g·kg BM of CHO. Venous blood was sampled at 30, 50, and 70 min and pre-warm-up and postexercise for the analysis of plasma PSE and catecholamine concentrations, and urine was also collected for the analysis of PSE concentration., Results: Independent of the preexercise meal, 2.8 mg·kg BM of PSE did not significantly improve cycling TT performance. The fed trials resulted in lower plasma PSE concentrations at all time points compared with the nonfed trials. Both plasma epinephrine and blood lactate concentrations were higher in the PSE compared with the PLA trials, and preexercise and postexercise urinary PSE concentrations were significantly higher than the threshold (150 μg·mL) used by WADA to determine illicit PSE use., Conclusion: Irrespective of the preexercise meal, cycling TT performance of approximately 30 min was not improved after PSE supplementation. Furthermore, 2.8 mg·kg BM of PSE taken 90 min before exercise, with or without food, resulted in urinary PSE concentrations exceeding the present WADA threshold.

Objectives: To investigate whether coinciding peak serum caffeine concentration with the onset of exercise enhances subsequent endurance performance., Design: Randomised, double-blind, crossover., Methods: In this randomised, placebo-controlled, double-blind crossover study, 14 male trained cyclists and triathletes (age 31±5year, body mass 75.4±5.7 kg, VO₂max 69.5±6.1 mL kg⁻¹ min⁻¹ and peak power output 417±35W, mean±SD) consumed 6 mg kg(-1) caffeine or a placebo either 1h (C(1h)) prior to completing a 40 km time trial or when the start of exercise coincided with individual peak serum caffeine concentrations (C(peak)). C(peak) was determined from a separate 'caffeine profiling' session that involved monitoring caffeine concentrations in the blood every 30 min over a 4h period., Results: Following caffeine ingestion, peak serum caffeine occurred 120 min in 12 participants and 150 min in 2 participants. Time to complete the 40 km time trial was significantly faster (2.0%; p=0.002) in C(1h) compared to placebo. No statistically significant improvement in performance was noted in the C(peak) trial versus placebo (1.1%; p=0.240). Whilst no differences in metabolic markers were found between C(peak) and placebo conditions, plasma concentrations of glucose (p=0.005), norepinephrine and epinephrine (p≤0.002) were higher in the C(1h) trial 6 min post-exercise versus placebo., Conclusions: In contrast to coinciding peak serum caffeine concentration with exercise onset, caffeine consumed 60 min prior to exercise resulted in significant improvements in 40 km time trial performance. The ergogenic effect of caffeine was not found to be related to peak caffeine concentration in the blood at the onset of endurance exercise., (Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

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 x kg(-1) x 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 x 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.

Unlabelled: Previous investigators have quantified fatigue during short maximal cycling trials ( approximately 30 s) by calculating a fatigue index. Other investigators have reported a curvilinear power-pedaling rate relationship during short fatigue-free maximal cycling trials (<6 s). During maximal trials, pedaling rates may change with fatigue. Quantification of fatigue using fatigue index is therefore complicated by the power-pedaling rate relationship., Purpose: The purpose of this study was to quantify fatigue while accounting for the effects of pedaling rate on power., Methods: Power and pedaling rate were recorded during Union Cycliste Internationale sanctioned 200-m time trials by eight male (height = 181.5 +/- 4.3 cm, mass = 87.0 +/- 8.0 kg) world-class sprint cyclists with SRM power meters and fixed-gear track bicycles. Data from the initial portion of maximal acceleration were used to establish maximal power-pedaling rate relationships. Fatigue was quantified three ways: 1) traditional fatigue index, 2) fatigue index modified to account for the power-pedaling rate relationship (net fatigue index), and 3) work deficit, the difference between actual work done and work that might have been accomplished without fatigue., Results: Fatigue index (55.4% +/- 6.4%) was significantly greater than net fatigue index (41.0% +/- 7.9%, P < 0.001), indicating that the power-pedaling rate relationship accounted for 14.3% +/- 7% of the traditional fatigue index value. Work deficit (23.3% +/- 6%) was significantly less than either measure of fatigue (P < 0.001)., Conclusion: Net fatigue index and work deficit account for the power-pedaling rate relation and therefore more precisely quantify fatigue during variable velocity cycling. These measures can be used to compare fatigue during different fatigue protocols, including world-class sprint cycling competition. Precise quantification of fatigue during elite cycling competition may improve evaluation of training status, gear ratio selection, and fatigue resistance.

Central hemodynamics such as ascending aortic blood pressure (BP), wave reflection and myocardial perfusion are clinically important in the context of cardiovascular health. Ultra-endurance athletes may be at greater risk of cardiovascular abnormalities due to chronically increased physiological stress placed on the cardiovascular system. This study was a cross-sectional investigation that compared central hemodynamics in ultra-endurance athletes and matched controls. Forty-four athletes (36 males; aged mean+/-S.D., 34+/-8 years) undergoing ultra-endurance training (16.3+/-3.7 h/week) were compared to 44 matched recreationally active (1.2+/-0.9 h/week) controls (36 males; aged 34+/-8 years). Brachial BP was measured using an oscillometric device while central hemodynamics including ascending aortic BP, wave reflection (augmentation index, AIx), ejection duration, sub-endocardial perfusion (SEVR) and timing of the reflected wave (T(R)) were determined by applanation tonometry and pulse wave analysis. There were no significant (P>0.05) differences between groups in AIx (athletes and controls; 6+/-12% versus 6+/-13%, respectively), T(R) (athletes and controls; 165+/-22 ms versus 165+/-19 ms, respectively), brachial (athletes and controls; 51+/-9 mmHg versus 48+/-12 mmHg, respectively) or central pulse pressure (33+/-5 mmHg versus 31+/-7 mmHg). However, athletes had significantly increased SEVR (226+/-42% versus 198+/-46%; P<0.001) despite having a longer ejection duration (348+/-19 ms versus 339+/-18 ms; P<0.05). Furthermore, the amount of exercise training volume was significantly related to central (r=-0.46; P=0.002), but not brachial pulse pressure (r=-0.28; P>0.05). Ultra-endurance athletes had increased sub-endocardial perfusion capacity and the quantity of exercise training was associated with central rather than peripheral hemodynamics.

Performance models provide an opportunity to examine cycling in a broad parameter space. Variables used to drive such models have traditionally been measured in the laboratory. The assumption, however, that maximal laboratory power is similar to field power has received limited attention. The purpose of the study was to compare the maximal torque- and power-pedaling rate relationships during "all-out" sprints performed on laboratory ergometers and on moving bicycles with elite cyclists. Over a 3-day period, seven male (mean +/- SD; 180.0 +/- 3.0 cm; 86.2 +/- 6.1 kg) elite track cyclists completed two maximal 6 s cycle ergometer trials and two 65 m sprints on a moving bicycle; calibrated SRM powermeters were used and data were analyzed per revolution to establish torque- and power-pedaling rate relationships, maximum power, maximum torque and maximum pedaling rate. The inertial load of our laboratory test was (37.16 +/- 0.37 kg m(2)), approximately half as large as the field trials (69.7 +/- 3.8 kg m(2)). There were no statistically significant differences between laboratory and field maximum power (1791 +/- 169; 1792 +/- 156 W; P = 0.863), optimal pedaling rate (128 +/- 7; 129 +/- 9 rpm; P = 0.863), torque-pedaling rate linear regression slope (-1.040 +/- 0.09; -1.035 +/- 0.10; P = 0.891) and maximum torque (266 +/- 20; 266 +/- 13 Nm; P = 0.840), respectively. Similar torque- and power-pedaling rate relationships were demonstrated in laboratory and field settings. The findings suggest that maximal laboratory data may provide an accurate means of modeling cycling performance.

We examined the influence of 3 consecutive days of high-intensity cycling on blood and urinary markers of oxidative stress. Eight highly-trained male cyclists (VO2 max 76 +/- 4 mL.kg-1.min-1; mean +/- SD) completed an interval session (9 exercise bouts lasting 30 s each, at 150% peak power output) on day 1, followed by 2 laboratory-simulated 30 km time trials on days 2 and 3. The cyclists also completed a submaximal exercise trial matched to the interval session for oxygen consumption. Blood was collected pre- and post-exercise for the determination of malondialdehyde (MDA), total antioxidant status (TAS), vitamin E, and the antioxidant enzyme activity of superoxide dismutase and glutathione peroxidase, while urine was collected for the determination of allantoin. There were significant increases in plasma MDA concentrations (p < 0.01), plasma TAS (p < 0.01), and urinary allantoin excretion (p < 0.01) following the high-intensity interval session on day 1, whereas plasma vitamin E concentration significantly decreased (p = 0.028). Post-exercise changes in plasma MDA (p = 0.036), TAS concentrations (p = 0.039), and urinary allantoin excretion (p = 0.031) were all significantly attenuated over the 3 consecutive days of exercise, whereas resting plasma TAS concentration was elevated. There were no significant changes in plasma MDA, TAS, or allantoin excretion following submaximal exercise and there were no significant changes in antioxidant enzyme activity over consecutive days of exercise or following submaximal exercise. Consecutive days of high-intensity exercise enhanced resting plasma TAS concentration and reduced the post-exercise increase in plasma MDA concentrations.

Introduction: Ultraendurance athletes who maintain a very high volume of exercise may, as a result of greater production of reactive oxygen species (ROS), be particularly susceptible to oxidative damage., Purpose: This study sought to examine and compare pre- and postrace markers of oxidative stress in ultraendurance athletes training for, and competing in, either a half or a full Ironman triathlon., Methods: Resting and postexercise blood was sampled from 16 half Ironman triathletes, 29 full Ironman triathletes, and age-matched, relatively inactive controls. Blood was analyzed for markers of oxidative stress (malondialdehyde (MDA) concentration) and antioxidant status (glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities)., Results: Compared with controls, the half Ironman triathletes had significantly (P < 0.001) higher erythrocyte GPX activity at rest, whereas the Ironman triathletes had significantly (P < 0.05) lower resting plasma MDA and significantly (P < 0.05) greater resting activities of GPX and CAT compared with controls. As a result of the half Ironman triathlon, there was a significant (P < 0.05) increase in MDA and significant (P < 0.05) decreases in erythrocyte GPX, SOD, and CAT activities. These changes also occurred in response to the Ironman triathlon; MDA significantly (P < 0.05) increased, and there were significant (P < 0.001) decreases in GPX, CAT, and SOD activities. Users of antioxidant supplements in both the half and full Ironman races had significantly (P < 0.05) elevated MDA after races compared with nonsupplementers., Conclusion: The present investigation indicates that training for and competing in half and full Ironman triathlons has different effects on erythrocyte antioxidant enzyme activities and oxidative stress.

The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean +/- s: age 35 +/- 6 years, height 1.77 +/- 0.05 m, mass 74.0 +/- 6.9 kg, = 4.75 +/- 0.42 l x min(-1)) performed progressive exercise tests of cycle ergometry and treadmill running for the determination of peak oxygen uptake (VO2peak), heart rate corresponding to the first and second ventilatory thresholds, as well as the heart rate deflection point. Portable telemetry units recorded heart rate at 60 s increments throughout the ultra-endurance triathlon. Heart rate during the cycle and run phases of the ultra-endurance triathlon (148 +/- 9 and 143 +/- 13 beats x min(-1) respectively) were significantly (P < 0.05) less than the second ventilatory thresholds (160 +/- 13 and 165 +/- 14 beats x min(-1) respectively) and heart rate deflection points (170 +/- 13 and 179 +/- 9 beats x min(-1) respectively). However, mean heart rate during the cycle and run phases of the ultra-endurance triathlon were significantly related to (r = 0.76 and 0.66; P < 0.01), and not significantly different from, the first ventilatory thresholds (146 +/- 12 and 148 +/- 15 beats x min(-1) respectively). Furthermore, the difference between heart rate during the cycle phase of the ultra-endurance triathlon and heart rate at the first ventilatory threshold was related to marathon run time (r = 0.61; P < 0.01) and overall ultra-endurance triathlon time (r = 0.45; P < 0.05). The results suggest that triathletes perform the cycle and run phases of the ultra-endurance triathlon at an exercise intensity near their first ventilatory threshold.

The purpose of the present study was to examine the influence of 3 different high-intensity interval training regimens on the first and second ventilatory thresholds (VT(1) and VT(2)), anaerobic capacity (ANC), and plasma volume (PV) in well-trained endurance cyclists. Before and after 2 and 4 weeks of training, 38 well-trained cyclists (Vo(2)peak = 64.5 +/- 5.2 ml.kg(-1).min(-1)) performed (a) a progressive cycle test to measure Vo(2)peak, peak power output (PPO), VT(1), and VT(2); (b) a time to exhaustion test (T(max)) at their Vo(2)peak power output (P(max)); and (c) a 40-km time-trial (TT(40)). Subjects were assigned to 1 of 4 training groups (group 1: n = 8, 8 x 60% T(max) at P(max), 1:2 work-recovery ratio; group 2: n = 9, 8 x 60% T(max) at P(max), recovery at 65% maximum heart rate; group 3: n = 10, 12 x 30 seconds at 175% PPO, 4.5-minute recovery; control group: n = 11). The TT(40) performance, Vo(2)peak, VT(1), VT(2), and ANC were all significantly increased in groups 1, 2, and 3 (p < 0.05) but not in the control group. However, PV did not change in response to the 4-week training program. Changes in TT(40) performance were modestly related to the changes in Vo(2)peak, VT(1), VT(2), and ANC (r = 0.41, 0.34, 0.42, and 0.40, respectively; all p < 0.05). In conclusion, the improvements in TT(40) performance were related to significant increases in Vo(2)peak, VT(1), VT(2), and ANC but were not accompanied by significant changes in PV. Thus, peripheral adaptations rather than central adaptations are likely responsible for the improved performances witnessed in well-trained endurance athletes following various forms of high-intensity interval training programs.

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 purpose of the present study was to examine, in highly trained cyclists, the reproducibility of cycling time to exhaustion (T(max)) at the power output equal to that attained at peak oxygen uptake (.VO2peak) during a progressive exercise test. Forty-three highly trained male cyclists (M +/- SD; age = 25 +/- 6 yrs; weight = 75 +/- 7 kg; .VO2peak = 64.8 +/- 5.2 ml.kg-1.min-1) performed two T(max) tests one week apart. While the two measures of T(max) were strongly related (r = 0.884; p < 0.001), T(max) from the second test (245 +/- 57 s) was significantly higher than that of the first (237 +/- 57 s; p = 0.047; two-tailed). Within-subject variability in the present study was calculated to be 6 +/- 6%, which was lower than that previously reported for T(max) in sub-elite runners (25%). The mean T(max) was significantly (p < 0.05) related to both the second ventilatory turnpoint (VT(2); r = 0.38) and to .VO2peak (r = 0.34). Despite a relatively low within-subject coefficient of variation, these data demonstrate that the second score in a series of two T(max) tests may be significantly greater than the first. Moreover, the present data show that T(max) in highly trained cyclists is moderately related to VT(2) and .VO2peak.

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.

Purpose: The purpose of this study was to examine the influence of three different high-intensity interval training (HIT) regimens on endurance performance in highly trained endurance athletes., Methods: Before, and after 2 and 4 wk of training, 38 cyclists and triathletes (mean +/- SD; age = 25 +/- 6 yr; mass = 75 +/- 7 kg; VO(2peak) = 64.5 +/- 5.2 mL x kg(-1) min(-1)) performed: 1) a progressive cycle test to measure peak oxygen consumption (VO(2peak)) and peak aerobic power output (PPO), 2) a time to exhaustion test (T(max)) at their VO(2peak) power output (P(max)), as well as 3) a 40-km time-trial (TT(40)). Subjects were matched and assigned to one of four training groups (G(2), N = 8, 8 x 60% T(max) at P(max), 1:2 work:recovery ratio; G(2), N = 9, 8 x 60% T(max) at P(max), recovery at 65% HR(max); G(3), N = 10, 12 x 30 s at 175% PPO, 4.5-min recovery; G(CON), N = 11). In addition to G(1), G(2), and G(3) performing HIT twice per week, all athletes maintained their regular low-intensity training throughout the experimental period., Results: All HIT groups improved TT(40) performance (+4.4 to +5.8%) and PPO (+3.0 to +6.2%) significantly more than G(CON) (-0.9 to +1.1%; P < 0.05). Furthermore, G(1) (+5.4%) and G(2) (+8.1%) improved their VO(2peak) significantly more than G(CON) (+1.0%; P < 0.05)., Conclusion: The present study has shown that when HIT incorporates P(max) as the interval intensity and 60% of T(max) as the interval duration, already highly trained cyclists can significantly improve their 40-km time trial performance. Moreover, the present data confirm prior research, in that repeated supramaximal HIT can significantly improve 40-km time trial performance.

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.