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“Priming exercises” are gaining popularity as a precompetition strategy to improve subsequent performance. Although priming exercise has been shown to improve various neuromuscular performance measures within 48 hours, a number of studies have also found no change or significant decreases in performance following priming interventions. Inconsistencies in findings are likely due to the many different variables used in the research. In addition, evidence suggests that the potential performance response following a priming stimulus is likely to be influenced by individual characteristics. Therefore, the purpose of this review is to examine the available evidence and identify those variables that most strongly determine whether priming stimuli involving resistance and stretch-shortening cycle exercise tasks are likely to improve performance within 48 hours of that stimulus. In addition to making recommendations based on the evidence to date, directions for future research are also identified.

In December 2013, the forward support company (FSC) with Task Force Attack, 3rd Battalion, 101st Aviation Regiment, 159th Combat Aviation Brigade, deployed to Afghanistan's Regional Command (RC) East to provide [...]

This article compares post-exercise levels of muscle and plasma glutamine and muscle glycogen in trained men on moderate or high-carbohydrate diets. Results indicate that plasma glutamine levels were higher in the high-carbohydrate group while there were no significant differences in muscle glutamine or glycogen concentrations between groups.

This study investigates the relationship between plasma lactate levels, muscle fiber characteristics, and endurance performance in female cyclists. Results indicate that a type of muscle fiber that impairs performance may result from increased production or decreased removal of lactate in larger, glycolytic muscle fibers.

Research remains inconclusive regarding benefits of strength training for female elite cyclists. Cyclists who underwent resistance training for the lower body and legs demonstrated improved repetition maximums for squatting exercises, but no significant benefits were noted for their average power output, peak oxygen consumption, lactate threshold or muscle fiber characteristics.

The net fatigue index and work deficit precisely quantify fatigue during variable velocity cycling. The measurement of fatigue may improve evaluation of training status, gear ratio selection, and fatigue resistance.

A study was conducted to examine the dose-response relationship of erythrocyte antioxidant enzyme activity and plasma oxidative stress in ultraendurance athletes training for and competing in half and full Ironman triathlons. The findings show that high-volume ultraendurance activity produces a significant decrease in resting malondialdehyde (MDA) concentration with athletes involved in full Ironman triathon training.

ABSTRACTObjectives: We examined: (1) relationships among sub-maximal heart rate (sub-maxHR) following 4 minutes of the Yo-Yo intermittent recovery test level 1 (IR1) and maximal-effort performance (distance covered at volitional exhaustion), (2) test re-test reliability of sub-maxHR, and (3) whether changes in maximal-effort Yo-Yo performance are related with changes in sub-maxHR in professional rugby league players.Methods: Yo-Yo IR1 performances of 32 players were assessed before and after 28.5 ± 6.8 days of pre-season training. Relationships between sub-maxHR and maximal-effort Yo-Yo performance, and changes in maximal-effort performance and sub-maxHR were compared.Results: Maximal-effort Yo-Yo IR1 performance and sub-maxHR correlated negatively (r = −0.73, CI −0.85 to −0.55, very large). Coefficient of variation (CV) of sub-maxHR was 2.4% (CI 2.0−3.3%), worthwhile changes of small(0.7 [CI 0.5−1.0%]), moderate(2.1 [CI 1.6−3.0%]) and large(4.3 [CI 3.3−6.1%]) were identified. Training-induced changes in sub-maxHR and Yo-Yo IR1 performance displayed a negative correlation (r = −0.57, CI −0.74 to −0.33, large).Conclusions: sub-maxHR has a very largenegative relationship with maximal-effort Yo-Yo IR1 performance. Training-induced changes in sub-maxHR demonstrated a largenegative relationship with changes in Yo-Yo IR1 performance. The CV and worthwhile changes can determine meaningful variations in sub-maxHR in professional rugby league players.

The influence of three different high-intensity training (HIT) regimens on endurance performance in highly trained endurance athletes is examined. The results show that HIT performed at intensities of Pmax and durations of 60% of Tmax is an effective means for enhancing 40-km time trial performance, peak power output in highly trained cyclists.

Faceted reflectors are a ubiquitous means for providing uniform illumination in many commercial lighting products, examples being newer flashlights, department-store display lighting, and the faceted reflectors found in overhead projectors. However, the design of faceted reflectors using software has often been more limited by the tools available to design them than by the imagination of the designers. One of the keys to enabling a broader range of design options has been to allow more complex surfaces using constructive solid geometry (CSG). CSG uses Boolean operations on basic geometric primitives to define shapes to create individual facets. In this paper, we describe an improved faceted reflector design algorithm and use it to create a wide range of CSG-based reflectors. The performance of various reflectors is compared using a Monte Carlo ray-trace method. © 2000 Society of Photo-Optical Instrumentation Engineers.

This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P > 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased.

The relationship between plasma lactate parameters, Wpeakand 1-h cycling performance in women.Med. Sci. Sports Exerc.,Vol. 30, No. 8, pp. 1270-1275, 1998.

The present investigation was conducted to determine whether critical power (CP) assesses the ability to perform continuous aerobic exercise and to determine whether training-induced changes in aerobic endurance are reflected by changes in the slope, but not the y-intercept of the CP function. Twelve healthy, active, but untrained male students (mean age ± SD = 19.1 ± 0.8 yr) undertook 8 wk of cycle ergometer endurance training (30–40 min a day, three times a week) at an intensity corresponding to their CP. Six control subjects of similar age and initial training status refrained from regular exercise for the same period. Before and immediately following the training period, each of the 18 participants completed three cycle ergometer tests to determine their CP function, an incremental exercise task to establish their maximal oxygen uptake (O2max), and 40 min of continuous cycle ergometry at or near their calculated CP. CP was significantly correlated with endurance time at 270 W (r = 0.65, P < 0.05) and with the mean power that could be maintained for 40 min (r = 0.87–0.95, P < 0.01), but overestimated the latter by less than 6. In response to endurance training, CP increased from a mean of 196 ± 40.9 W to 255 ± 28.4 W (31) (ANCOVA, P < 0.01), while the mean power output maintained for 40 min of exercise increased from 190 ± 34.5 W to 242 ± 34.9 W (28). O2maxincreased from 49.2 ± 7.8 ml.kg−1.min−1to 53.4 ± 6.4 ml.kg−1.min−1(8.5) (P < 0.01). The y-intercept of the CP function did not change significantly with aerobic endurance training. CP appears to provide a useful practical means of monitoring aerobic endurance ability and an individual's response to training, while avoiding the problems of the measurement of thresholds and criteria based on fixed blood lactate concentrations.

Six men were studied during four 30-s “all-out” exercise bouts on an air-braked cycle ergometer. The first three exercise bouts were separated by 4 min of passive recovery; after the third bout, subjects rested for 4 min, exercised for 30 min at 30–35% peak O2consumption, and rested for a further 60 min before completing the fourth exercise bout. Peak power and total work were reduced (P< 0.05) during bout 3[765 ± 60 (SE) W; 15.8 ± 1.0 kJ] compared withbout 1(1,168 ± 55 W, 23.8 ± 1.2 kJ), but no difference in exercise performance was observed betweenbouts 1and4(1,094 ± 64 W, 23.2 ± 1.4 kJ). Before bout 3, muscle ATP, creatine phosphate (CP), glycogen, pH, and sarcoplasmic reticulum (SR) Ca2+uptake were reduced, while muscle lactate and inosine 5′-monophosphate were increased. Muscle ATP and glycogen before bout 4remained lower than values beforebout 1(P< 0.05), but there were no differences in muscle inosine 5′-monophosphate, lactate, pH, and SR Ca2+uptake. Muscle CP levels before bout 4had increased above resting levels. Consistent with the decline in muscle ATP were increases in hypoxanthine and inosine before bouts 3and 4. The decline in exercise performance does not appear to be related to a reduction in muscle glycogen. Instead, it may be caused by reduced CP availability, increased H+concentration, impairment in SR function, or some other fatigue-inducing agent.

It has been shown that when three periods of exercise at different intensities are performed to exhaustion, the linear regression of the work accomplished on the time taken defines the critical power (CP) function. The slope of this function is related to endurance ability, whereas the y-intercept is considered to represent anaerobic work capacity (AWC). The purpose of this study was to determine whether two different recovery durations (3 and 24 h), separating three periods of exercise, would elicit differences in the linear CP function. Nine healthy, untrained female students [19.5 (SD 1.6) years] completed five sessions of cycle exercise to exhaustion in random order (familiarisation). Three of these five power outputs were then used in the main part of the study in which the subjects were randomly assigned to two groups. Group one first performed the three power outputs on the same day, with 3 h of passive recovery separating each session (3 on 1). Group two first performed the three power outputs on 3 consecutive days, with approximately 24 h between sessions (3 con). Following 1 day of rest, group one repeated their three power outputs on 3 consecutive days and group two completed their three tests on the same day. Repeated-measures ANOVA revealed no significant differences between the mean values of CP or AWC calculated from the 3 on 1 or 3 con conditions. Trial two estimates of CP were, however, 3.4% (P < 0.05) higher than trial one (familiarisation) estimates. The results of this study showed that reliable measurements of both CP and AWC can be determined from three tests separated by rest periods of 3 h, provided that the subjects are first familiarised with the tests. We found one series of five exercise sessions to be sufficient familiarisation to ensure similar subsequent estimates of CP.

The purposes of this investigation were to determine the validity of critical power (CP) as a measure of the work rate that can be maintained for a very long time without fatigue and to determine whether this corresponded with the maximal lactate steady-state (lass,max). Eight highly trained endurance cyclists (maximal oxygen uptake 74.1 ml · kg-1 · min-1, SD 5.3) completed four cycle ergometer tests to exhaustion at predetermined work rates (360, 425, 480 and 520 W). From these four co-ordinates of work and time to fatigue the regression of work limit on time limit was calculated for each individual (CP). The cyclists were then asked to exercise at their CP for 30 min. If CP could not be maintained, the resistance was reduced minimally to allow the subject to complete the test and maintain a blood lactate plateau. Capillary blood was sampled at 0, 5, 10, 20 and 30 min into exercise for the analysis of lactate. Six of the eight cyclists were unable to maintain CP for 30 min without fatigue. In these subjects, the mean power attained was 6.4% below that estimated by CP. Mean blood lactates (n = 8) reached a steady-state (8.9 mmol · l-1, SD 1.6) during the last 20 min of exercise indicating that CP slightly overestimated lass, max. Individual blood lactates during the last 20 min of exercise were more closely related to the y-intercept of the CP curve (r=0.78, P<0.05) than either CP (0.34, NS) or mean power output (r=0.42, NS). The present investigation has shown that highly trained endurance cyclists can tolerate previously unreported levels of blood lactate during 30 min of exercise at or near their CP. Blood lactates during continuous exercise are higher than at the same work rate during an incremental test. The CP provides a simple and inexpensive means of assessing the exercise intensity which can be maintained continuously, while avoiding the methodological difficulties associated with ventilatory and lactate thresholds.

JENKINS, D. G. and B. M. QUIGLEY. The influence of high intensity exercise training on the Wlim-Tlimrelationship. Med Sci. Sports Exerc.,Vol. 25, No. 2, pp. 275–282, 1993. When exercise to exhaustion is performed using at least two different intensities, work to fatigue (Wlim) can be expressed as a linear function of time to fatigue (Tlim). Whereas the slope of this function is related to endurance ability, the y-intercept is associated with the potential to perform high intensity interval exercise. The purpose of the present investigation was to determine the influence of 8-wk intermittent high-intensity exercise training on the y-intercept derived from the Wlim-Tlimrelationship. Eight healthy, untrained male students (19.1 ± 0.6 yr) completed five 60-s bouts of maximal exercise on the cycle ergometer, three times a week, for 8 wk. Seven controls avoided regular activity for the same period. Prior to and immediately following the training period, the Wlim-Tlimrelationship, VO2max, and total work completed in five 60-s exercise bouts on the cycle ergometer were determined. Correlational analysis established relationships between the y-intercept and total work accomplished in the interval test pre- (r = 0.90; P< 0.01; N= 15) and post-training (r = 0.92; P< 0.01; N= 15), confirming that the y-intercept is related to the ability to perform exercise of this nature. Moreover, the “anaerobic” energy yield, calculated from total work and oxygen consumed during the interval exercise, was also related to the y-intercept (r = 0.78; P< 0.01). Interval training significantly increased both the y-intercept (P= 0.0015) and total work accomplished in the interval test (P= 0.001), while the slope of the Wlim-Tlimrelationship (critical power) remained unchanged. Changes in the y-intercept were correlated to changes in total work accomplished (r = 0.85; P0.01). Furthermore, peak post-exercise plasma lactate concentration resulting from the interval task increased from 12.2 ± 1.6 to 16.3 ± 0.9 mmol.−1(P= 0.003), while oxygen consumed during this exercise demand was not significantly changed with training (P= 0.166). The present study has demonstrated that not only does the y-intercept of the Wlim-Tlimrelationship provide a measure of the ability to undertake repeated bouts of maximal, high intensity exercise, but that this particular characteristic is also responsive to exhaustive interval training.

The standard critical power test protocol on the cycle ergometer prescribes a series of trials to exhaustion, each at a different but constant power setting. Recently the protocol has been modified and applied to a series of trials to exhaustion each at a different ramp incremental rate. This study was undertaken to compare critical power and anaerobic work capacity estimates in the same group of subjects when derived from the two protocols. Ten male subjects of mixed athletic ability cycled to exhaustion on eight occasions in randomized order over a 3-wk period. Four trials were performed at differing constant power settings and four trials on differing ramp incremental rates. Both critical power and anaerobic work capacity were estimated for each subject by curve fitting of the ramp model and of three versions of the constant power model. After adjusting for inter-subject variability, no significant differences were detected between critical power estimates or between anaerobic work capacity estimates from any model formulation or from the two protocols. It is concluded that both the ramp and constant power protocols produce equivalent estimates for critical power and anaerobic work capacity.

MACKINNON, L. T. and D. G. JENKINS. Decreased salivary immunoglobulins after intense interval exercise before and after training. Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 678–683, 1993. Endurance athletes have been shown to suffer a high incidence of upper respiratory tract infection (URTI). Previous studies have shown that concentration and flow rate of secretory immunoglobulin A (IgA), the major effector of host resistance to URTI, decrease after intense endurance exercise. The purpose of this study was to determine whether salivary IgA concentration and flow rate decrease after brief intense interval exercise, and whether the response to exercise changes with training. Twelve male subjects performed five 60-s bouts of supramaximal interval exercise at 0.075 g.kg-1body mass on a cycle ergometer; each bout was separated by 5-min rest. Subjects then trained for 8 wk by performing the same interval exercise protocol three times per week. Timed, whole unstimulated saliva samples were obtained before and after the interval exercise protocol, before and after training. Salivary IgA, IgG, and IgM concentrations were measured by ELISA and flow rates calculated. IgA and IgM concentrations relative to total protein decreased after each exercise session; IgG concentration relative to total protein did not change after exercise. IgA, IgM, and IgG flow rates decreased 50–65 after interval exercise. There was no effect of training on any immune parameter measured, although total work performed in the five 60-s bouts increased after training. These data show that the output of salivary IgA and IgM decrease after brief supramaximal interval exercise, and that the decreased output is due, at least partially, to the decrease in saliva flow. In addition, there appears to be a specific effect of intense exercise on IgA concentration greater than that due to decreased saliva flow alone. These data suggest that decreases in secretory IgA output after repeated bouts of supramaximal exercise may be one mechanism contributing to the high incidence of upper respiratory tract infection among athletes.

When bouts of muscular work are performed to exhaustion at different intensities, the slope of the regression of maximal work (work limit) on maximal time (time limit) is referred to as critical power (CP). The y-intercept of this function is considered to represent anaerobic work capacity (AWC). The purpose of this investigation was to examine the relationship between the y-intercept from the critical power curve and measures of AWC (total work accomplished, maximal blood lactate and post-exercise venous blood pH) gained from repeated, maximal exercise. Nine male volunteers of moderately high training status (V˙O2max 4·45 ±0·251/min) completed three cycle ergometer tests to exhaustion (at 300, 350 and 400 W) for the determination of CP. A second cycle ergometer task involved repeated maximal effort (against 0075N/kg body mass) over five 1 min periods. Five min of passive recovery separated each exercise bout, at the end of which capillary blood was collected for lactate analysis. On completion of the fifth bout, venous blood was sampled for the determination of blood pH. Total accumulated work provided a performance estimate of AWC which, together with blood lactate and pH, was compared to the y-intercept. Correlation analysis revealed a significant relation between the y-intercept and total work accomplished (r=0·74; p<0·05), while post-exercise venous blood pH was positively related to both the y-intercept (r7equals;0·92; p<0·01) and the accumulated work recorded (r=0·92; p<0·01). No significant correlation between peak blood lactate and work was found (r=0·16; ns), although a relation between post-exercise venous blood pH and V˙O2max was established (r=0·84; p <0·05). The capacity for high intensity interval work was well represented by the y-intercept in active males. Furthermore, the relations between blood pH and both the y-intercept and accumulated work suggest that either improved buffering or a greater contribution of aerobic metabolism to the energy yield may have been responsible for the more successful performances in the interval exercise.

The present study investigated the relationship between plasma potassium ion concentration ([K +]) and skeletal muscle torque during three different 15-min recovery periods after fatigue induced by four 30-s sprints. Four males and one female completed the multiple sprint exercise on three separate days; recovery was passive, i.e. no cycling exercise (PRec), active cycling at 30% peak oxygen consumption $\dot V$ O 2peak (30% Rec) and active cycling at 60% $\dot V$ O 2peak (60% Rec). Plasma [K +] was measured from blood sampled from an antecubital vein of subjects at rest and at 0, 3, 5, 10 and 15 min into each recovery. Isokinetic leg strength was measured at rest and at 1, 6, 11 and 16 min during each recovery. Following the exhaustive sprints, [K +] increased significantly from an average mean (SEM) resting value of 3.81 (0.07) mmol?·?l -1 to 4.48 (0.19) mmol?·?l -1 ( P?+] returned to resting levels within 3 min following the fourth sprint. However, in the two active recovery conditions plasma [K +] increased over the remainder of the recovery periods to 4.36 (0.12) mmol?·?l -1 in the 30% Rec condition and 4.62 (0.12) mmol?·?l -1 in the 60% Rec condition, the latter being significantly higher than the former ( P?+] across all three recovery conditions, muscle torque recovery was significantly different in only the 30% Rec condition. In summary, recovery of peak levels of muscle torque following fatiguing exercise does not appear to follow changes in plasma [K +].

The article focuses on the study concerning the improvement of low-cholesterol diet by the addition of monounsaturated fat (MUFA) led by professor David Jenkins. It says that study is comprising 24 patients who completed very low-saturated fat diet before being assigned to either high-MUFA diet. The researchers suggests that en elevation in cholesterol levels were found in patients who consumed elevated levels of MUFA.