Reliability and validity of test concepts for the cross-country skiing sprint

PURPOSE: This study was conducted, first, to develop a test concept for the new cross-country (XC) skiing sprint and to check test reliability and validity, and, secondly, to test the hypothesis that short-duration maximal speed in double poling (DP) predicts DP sprint performance over race distance (1000-1500 m). METHODS: A total of 31 elite XC skiers performed test-retest of a 50-m DP sprint test (DP50m) and a subgroup (N = 17) performed test-retest of a DP sprint speed test (DPVmax) and a 1000-m DP sprint test (DP1000m), both on a treadmill. Additionally, 17 subjects performed all three tests to check validity, whereas six subjects performed an additional 1000-m DP field test. All tests were performed on roller skis. RESULTS: The DP50m, DPVmax, and DP1000m were reliable (r = 0.78-0.99, P < 0.001, CV = 0.79-6.18). The 50-m time (t50) and maximal velocity (Vmax50) of DP50m correlated to the maximal velocity (Vmax) in the DPVmax-test (r = -0.90; r = 0.86; P < 0.001), and time in the DPfield-test (tfield) correlated (r = 0.96, P < 0.01) to time in the DP1000m-test (t1000), showing validity of all treadmill tests. t50, Vmax50, Vmax, and fatigue index (FI) correlated to t1000 (r = 0.87; r = -0.85; r = -0.95; r = 0.86, P < 0.001). CONCLUSIONS: Cross-country skiing DP sprint tests appear reliable, valid, and standardizable. The relationship of maximal DP speed on DP sprint performance over race distance suggests (a) to integrate short-time sprint tests as predictors for XC sprint skiing performance, and (b) to reconsider the role of XC skiing specific speed training as an additional instrument to improve XC skiing sprint performance.     

Analysis of a simulated sprint competition in classical cross country skiing

The objectives of this project were first to analyze the physiological response of a classical cross country (XC) skiing sprint competition, second, to examine the relationships of kinematic and physiological variables with sprint performance and third, to test the hypothesis that maximal speed in double poling (DP) and diagonal stride (DIAG) predicts sprint performance. Twelve elite skiers performed a treadmill-based simulation of a sprint competition that included two maximal speed tests (DP, DIAG), a test and three sprint heats over a 3.5-h period. VO(2), lactate, heart rate (HR) and kinematic variables were measured. Maximal DP and DIAG speed, the level of repeatedly produced lactate values and skiing technical aspects positively correlated with sprint performance. Fastest skiers produced longer cycle lengths in all techniques at equal poling frequency. VO(2) variables showed no correlation to sprint performance. VO(2), tidal volume (VT), and lactate decreased over the heats. XC-sprint performance in classical style depends on speed abilities, technique use, fatigue resistance, and anaerobic capacity. The relationship of maximal speed with sprint performance suggests (a) integrating maximal speed tests in XC sprint diagnostics and (b) emphasizing training models for XC skiing-specific speed abilities to improve performance in XC skiing sprint.     

Effects of creatine supplementation on muscle power, endurance, and sprint performance

PURPOSE: To determine the effects of creatine (Cr) supplementation (20 g x d(-1) during 5 d) on maximal strength, muscle power production during repetitive high-power-output exercise bouts (MRPB), repeated running sprints, and endurance in handball players. METHODS: Nineteen trained male handball players were randomly assigned in a double-blind fashion to either creatine (N = 9) or placebo (N = 10) group. Before and after supplementation, subjects performed one-repetition maximum half-squat (1RM(HS) and bench press (1RM(BP)), 2 sets of MRPB consisting of one set of 10 continuous repetitions (R10) followed by 1 set until exhaustion (R(max)), with exactly 2-min rest periods between each set, during bench-press and half-squat protocols with a resistance equal to 60 and 70% of the subjects' 1RM, respectively. In addition, a countermovement jumping test (CMJ) interspersed before and after the MRPB half-squat exercise bouts and a repeated sprint running test and a maximal multistage discontinuous incremental running test (MDRT) were performed. RESULTS: Cr supplementation significantly increased body mass (from 79.4 +/- 8 to 80 +/- 8 kg; P < 0.05), number of repetitions performed to fatigue, and total average power output values in the R(max) set of MRPB during bench press (21% and 17%, respectively) and half-squat (33% and 20%, respectively), the 1RM(HS) (11%), as well as the CMJ values after the MRPB half-squat (5%), and the average running times during the first 5 m of the six repeated 15-m sprints (3%). No changes were observed in the strength, running velocity, or body mass measures in the placebo group during the experimental period. CONCLUSION: Short-term Cr supplementation leads to significant improvements in lower-body maximal strength, maximal repetitive upper- and lower-body high-power exercise bouts, and total repetitions performed to fatigue in the R(max) set of MRPB, as well as enhanced repeated sprint performance and attenuated decline in jumping ability after MRPB in highly trained handball players. Cr supplementation did not result in any improvement in upper-body maximal strength and in endurance running performance.     

Leg power and hopping stiffness: relationship with sprint running performance

PURPOSE: Although sprint performance undoubtedly involves muscle power, the stiffness of the leg also determines sprint performance while running at maximal velocity. Results that include both of these characteristics have not been directly obtained in previous studies on human runners. We have therefore studied the link between leg power, leg stiffness, and sprint performance. METHODS: The acceleration and maximal running velocity developed by 11 subjects (age 16 +/- 1) during a 40-m sprint were measured by radar. Their leg muscle volumes were estimated anthropometrically. Leg power was measured by an ergometric treadmill test and by a hopping test. Each subject executed a maximal sprint acceleration on the treadmill equipped with force and speed transducers, from which forward power was calculated. A hopping jump test was executed at 2 Hz on a force platform. Leg stiffness was calculated using the flight and contact times of the hopping test. RESULTS: The treadmill forward leg power was correlated with both the initial acceleration (r = 0.80, P < 0.01) and the maximal running velocity (r = 0.73, P < 0.05) during track sprinting. The leg stiffness calculated from hopping was significantly correlated with the maximal velocity but not with acceleration. CONCLUSION: Although muscle power is needed for acceleration and maintaining a maximal velocity in sprint performance, high leg stiffness may be needed for high running speed. The ability to produce a stiff rebound during the maximal running velocity could be explored by measuring the stiffness of a rebound during a vertical jump.     

Specificity of test duration when assessing the anaerobic lactacid capacity of high-performance track cyclists

The specificity of three maximal cycling sprint tests as a measure of anaerobic lactacid capacity was determined in nine highly trained male cyclists when they performed 10-, 30-, 40-, and 60-s tests on a modified Repco wind-braked cycle ergometer. Peak power (PP), percent power loss (% PO), total work done (TW), and peak blood lactate (PHLa) were determined for each test. The cyclists also performed a 1000-m time trial under competition conditions during which 200-m split times, total time (TT), and peak post-competition blood lactate (TTPHLa) were recorded. While there was no statistically significant difference between the peak blood lactate of the 30-, 40-, and 60-s tests, peak blood lactate achieved after the 1000-m time trial was significantly greater than those after the cycle ergometer tests. Although there were high intercorrelations (0.88-0.99) between the anaerobic power and capacity indices of the laboratory tests, only the PP and TW achieved during the 60-s test correlated significantly (P less than 0.05) with TT. The data suggest that when assessing the anaerobic power and capacity of elite 1000-m time trial cyclists, a cycle ergometer test duration of at least 60 s should be employed.     

Differences in physical fitness and throwing velocity among elite and amateur female handball players

This study compared physical characteristics (body height [BH], body mass [BM], body fat [BF], and fat free mass [FFM]), one repetition maximum bench press (1RM (BP)), jumping explosive power (VJ), handball throwing velocity, power-load relationship of the leg and arm extensor muscles, 5- and 15-m sprint running time, and running endurance in elite (n = 16; EF) and amateur (n = 15; AF) female handball players aged 17 - 38. Results revealed that, compared to AF, EF players presented similar values in body mass and percent body fat, but higher values (p < 0.001 - 0.05) in BH (6 %), FFM (10 %), 1RM (BP) (23 %), VJ (10 %), handball throwing velocity (11 %), power-load relationship of the arm (25 %) and leg (12 %) extensors, as well as 5- and 15-m sprint (3 - 4 %) and endurance running velocities (13 %). Univariate regression analyses showed that 1RM (BP) was associated with throwing velocity (R (2) = 0.64). The higher absolute values of maximal strength and muscle power, although explained by the differences in fat free mass, will give EF an advantage to sustain certain handball game actions. The association between 1RM (BP) and throwing velocity suggests that throwing velocity values in female handball players depend more on maximal strength than on the capacity to move low loads at high velocities, during elbow extension actions.     

Method of lactate elevation does not affect the determination of the lactate minimum

PURPOSE: The aim of the study was to examine the effects of different lactate elevation protocols on the determination of the lactate minimum (Lac(min)) point. METHODS: Eight highly trained racing cyclists each completed four continuous ramp lactate minimum tests using the following blood lactate elevation protocols: 1) continuous ramp maximal aerobic power (RMP(max)) assessment, 2) 30-s maximal sprint, 3) 40-s maximal sprint, and 4) two 20-s maximal sprints separated by a 1-min recovery. Each blood lactate elevation protocol was followed by a 5-min active recovery leading into a continuous ramp test commencing at a power of 60% of RMP(max), using a 6 W x min ramp rate, lasting 15 min. RESULTS: Peak [La](b) values were significantly higher (P > 0.05) after the RMP(max) compared with all other protocols and higher in the 40-s versus 30-s sprint. However, by the start of Lac(min) ramp, [La](b) after the RMP(max) was no longer higher than the 40-s sprint, but Lac(min) [La](b) was similar for all protocols. This resulted in no differences in the total decline of [La](b) measured as a percentage from the highest to the lowest value. At Lac(min) point, there were no significant differences in power (P > 0.05), but heart rate was higher in the RMP versus 2 x 20 s and VO(2) was significantly higher after the 40 s compared with the 2 x 20 s protocol. CONCLUSION: This study demonstrated that the determination of lactate minimum power in cycling is not dependent upon the lactate elevation protocol.     

Bicycle ergometry and speed skating performance

A comparison between maximal power output during cycling and skating was made, and correlates of skating performance with bicycle performance and skating technique were investigated. Twenty-five well-trained speed skaters performed two bicycle tests and a 500-m and 1500-m ice skating race. The power (P) during skating is calculated from ice and air friction losses: at 500 m P500 = 344 +/- 60 W and at 1500 m P1500 = 283 +/- 65 W. Stroke frequency and pre-extension knee angle as principle determining factors of P were determined. The two bicycle tests (of 30" and 2'30" duration, maximal performance) yield P30C = 875 +/- 86 W and P2.30C = 420 +/- 52 W with VO2max = 4.76 +/- 0.45 l/min. The highest correlate of P500 as well as of P1500 appeared to be P30C, respectively, r = 0.78 and r = 0.85. Correlation coefficients between the power during skating and P2.30C or VO2max have a value of about 0.6. If the stroke frequency and P30C are correlated with the power during skating, then high multiple correlation coefficients are obtained: at 500 m R = 0.85 and at 1500 m R = 0.90. The correlation of P30C suggests that the interindividual differences of skating performance at 500-m and 1500-m distances can be attributed substantially to differences in anaerobic power. Yet, the predictive value of the bicycle test for speed skating performance is low. The difference observed between maximal power output during cycling and skating is discussed.     

Fatigue during a 5-km running time trial

This study investigated fatigue-induced changes in neuromuscular and stride characteristics during and immediately after the 5-km running time trial. Eighteen well-trained male distance runners performed a maximal 20-m sprint test and maximal voluntary contraction (MVC) in a leg press machine before and immediately after the 5-km running time trial. In all the tests the EMG of five lower limb muscles was measured. The results of the present study showed that muscle fatigue measured in maximal exercises like 20-m sprint and MVC are not related to the fatigue induced changes during the 5-km time trial. The fatigue in the 20-m sprint test was related to the maximal 20-m pretest velocity (r = 0.58, p < 0.05), but the velocity loss during the 5-km time trial was inversely related to 5-km performance (r = - 0.60, p < 0.05) and training volume (r = - 0.58, p < 0.05). It was concluded that the fatigue in 5-km running measured pre- and postexercise at maximal effort is more related to sprint performance rather than endurance performance, but the fatigue measured during the 5-km running is related to endurance performance and factors affecting pacing strategy.     

Relationship between measured maximal oxygen uptake and aerobic endurance performance with running repeated sprint ability in young elite soccer players

AIM: The aim of the study was to determine the relationships between maximal oxygen uptake (VO(2max)) in a maximal treadmill run and the aerobic endurance performance in the 20-m multistage shuttle run (MST) test, with the performance indices obtained in the running repeated sprint ability (rRSA) test, in elite youth soccer players. METHODS: Thirty-seven adolescent male outfield players performed on separate days and in random order the treadmill run test and the MST, to obtain their measured VO(2max) and aerobic endurance performance (via the number of completed shuttles in the MST), respectively. Players also completed the rRSA test of 6x20-m all-out sprints, interspersed with 20 s of active recovery. RESULTS: There was a significant moderate correlation between measured VO(2max) (in L . min(-1) and mL . kg(-1) . min(-1)) and MST results (r=0.43 and 0.54, P<0.05, respectively). There was no significant correlation between measured VO(2max) and aerobic endurance performance with any of the performance indices in the rRSA test (all P>0.05). CONCLUSION: The moderate association between the measured VO(2max) and MST suggests that both tests were plausibly measuring different aspects of a player's aerobic fitness. The lack of association between measured VO(2max) and aerobic endurance performance in the MST with performance in the rRSA suggests that aerobic fitness per se is poorly associated with performance in the rRSA in elite youth soccer players.     

Effect of acute hypoxia on maximal oxygen uptake and maximal performance during leg and upper-body exercise in Nordic combined skiers

We examined the effect of normobaric hypoxia (3200 m) on maximal oxygen uptake (VO2max) and maximal power output (Pmax) during leg and upper-body exercise to identify functional and structural correlates of the variability in the decrement of VO2max (DeltaVO2max) and of maximal power output (DeltaPmax). Seven well trained male Nordic combined skiers performed incremental exercise tests to exhaustion on a cycle ergometer (leg exercise) and on a custom built doublepoling ergometer for cross-country skiing (upper-body exercise). Tests were carried out in normoxia (560 m) and normobaric hypoxia (3200 m); biopsies were taken from m. deltoideus. DeltaVO2max was not significantly different between leg (-9.1+/-4.9%) and upper-body exercise (-7.9+/-5.8%). By contrast, Pmax was significantly more reduced during leg exercise (-17.3+/-3.3%) than during upper-body exercise (-9.6+/-6.4%, p<0.05). Correlation analysis did not reveal any significant relationship between leg and upper-body exercise neither for DeltaVO2max nor for DeltaPmax. Furthermore, no relationship was observed between individual DeltaVO2max and DeltaPmax. Analysis of structural data of m. deltoideus revealed a significant correlation between capillary density and DeltaPmax (R=-0.80, p=0.03), as well as between volume density of mitochondria and DeltaPmax (R=-0.75, p=0.05). In conclusion, it seems that VO2max and Pmax are differently affected by hypoxia. The ability to tolerate hypoxia is a characteristic of the individual depending in part on the exercise mode. We present evidence that athletes with a high capillarity and a high muscular oxidative capacity are more sensitive to hypoxia.     

Motor abilities and anthropometrics in youth cross‐country skiing

The purposes were to validate whether general motor abilities and anthropometrics are determinants of youth cross‐country (XC) skiing performance; evaluate gender‐specific differences; and to establish noninvasive diagnostics. Fifty‐one youth XC skiers (34 boys; 13.8 ± 0.6 years and 17 girls; 13.4 ± 0.9 years) performed motor skill and laboratory tests, and anthropometric data were collected and correlated with XC skiing performance. Anthropometrics and maturity status were related to boys but not to girls XC skiing performance. Push‐ups and 20‐m sprint were correlated to XC skiing performance in both boys and girls. XC skiing performance of boys was predominantly influenced by upper body and trunk strength capacities (medicine ball throw, push‐ups, and pull‐ups) and jumping power (standing long and triple jump), whereas XC skiing of girls was mainly influenced by aerobic capacities (3000‐m run). Laboratory measures did not reveal greater correlations to XC skiing performance compared with simple test concepts of speed, strength, and endurance. Maturity was a major confounding variable in boys but not girls. Use of noninvasive simple test concepts for determination of upper body strength, speed, and endurance represent practicable support for ski clubs, schools, or skiing federations in the guidance and evaluation of young talent, being aware of the effect of maturity especially in boys.     

Effects of an entire season on physical fitness changes in elite male handball players

PURPOSE: Fifteen elite male handball players were studied to examine the effects of an entire season of play on physical fitness and throwing velocity. METHODS: One repetition maximal bench press (1RMBP), jumping explosive strength, power-load relationship of the leg and arm extensor muscles, 5- and 15-m sprint running time, endurance running, and handball throwing velocity (standing and three-step running throw) were assessed on four times (T1, T2, T3, and T4), during a 45-wk season. Individual volumes and intensities of training and competition were quantified for 11 activities. RESULTS: From T1 to T3, significant increases occurred in free fatty mass (1.4%), 1RMBP (1.9%), standing throwing velocity (6.5%), and three-step throwing velocity (6.2%). No significant changes were observed throughout the season in endurance running and explosive strength-related variables. Significant correlations (P < 0.05-0.01) were observed between strength training time and changes in standing throwing velocity as well as between high-intensity endurance training time and changes in endurance running. In addition, linear inverse relationships were observed between low-intensity endurance training time and changes in muscle power output of the lower extremities. CONCLUSION: The handball season resulted in significant increases in maximal and specific strength of the upper-extremity but not in the lower-extremity actions. The correlations observed suggest that training time at low intensity should be given less attention, whereas the training stimuli for high-intensity endurance running and leg strength training should be given more careful attention in the full training season program.     

The application of soccer performance testing protocols to the non-elite player

AIM: The application of performance testing for the evaluation of non-elite soccer players has received little attention. The purpose of this investigation was to use tests developed for elite soccer players to evaluate performance in non-elite soccer players and compare performance test results between elite (literature) and non-elite (data) players. METHODS: Thirteen male soccer players volunteered to participate. The tests included a treadmill VO2max test, 20 m sprint, vertical jump (VJ), 30 s Wingate cycle ergometer test, the Loughborough Intermittent Shuttle Test (LIST), and 2 20-m multi-stage shuttle runs to exhaustion (fatigue test). Actual VO2max (absolute and relative) scores were correlated with the estimated VO2max scores (fatigue test), 20 m sprint, VJ, and 30 s Wingate using a Pearson's product-moment correlation. A paired t-test was conducted on the fatigue test trials. RESULTS: Non-significant relationships were observed between actual VO2max scores and estimated VO2max from the fatigue test (absolute and relative terms). Non-significant relationships were also observed between peak and average power output (Wingate), 20 m sprint, and VJ. Mean heart rates (HRs) throughout the LIST was 165+/-7 bpm, which represented 88% of HRmax. CONCLUSIONS: The results of this study demonstrate that to elicit physiological differences between elite and non-elite players, assessment must include both an aerobic and anaerobic component.     

Fatigue induced by a cross-country skiing KO sprint

PURPOSE: The aims of the present study were 1) to analyze whether the KO sprint simulation induced a phenomenon of fatigue of upper and lower limbs and 2) if there was any fatigue, to determine its origin. METHODS: Seven elite male skiers were tested before and after a simulation of KO sprints consisting of three 1200-m laps separated by 12 min of recovery. Surface electromyographic activity and force obtained under voluntary and electrically evoked contractions (single twitch) on knee-extensor muscles were analyzed to distinguish neural adaptations from contractile changes. A maximal power output test of the upper limbs was also performed. RESULTS: During the last lap, the final sprint velocity was significantly lower than during the first lap. After the KO sprint, knee-extensor voluntary (-9.8 +/- 9.5%) and evoked (-16.2 +/- 11.9%) isometric force and upper-limb power output (-11.0 +/- 9.3%) and force (-11.3 +/- 8.7%) significantly decreased, whereas the blood lactate concentration increased to 11.6 mM. On the other hand, no changes were seen in RMS measurement during maximal voluntary contractions, RMS normalized by M-wave amplitude, or M-wave characteristics. CONCLUSION: Changes in performance, lactate concentration, knee-extensor strength, and upper-limb power indicated that the KO sprint test led the skiers to a state of fatigue. On lower-limb muscles, the decrease of knee-extensor strength was exclusively caused by peripheral fatigue, which was at least in part attributable to a failure of the excitation-contraction coupling.     

An evaluation of tests of anaerobic power

The objectives of this study were to examine the relationships between two recently developed laboratory tests of anaerobic power (AnP) and to compare these tests to other measures of AnP. Fifteen male subjects, aged 20-34 years, performed: a 30-s maximal cycle ergometer test (Wingate test), a 60-s isokinetic knee extension test (isokinetic endurance test), a 50-m sprint, a 200-m sprint, and the Margaria stair-climb test. Significant correlations ranging from 0.52-0.76 were found between the Wingate and isokinetic endurance tests for peak and mean values of power and torque, respectively. Indices from both these tests also correlated significantly with the other tests of AnP. The best single index was mean power from the Wingate test, which had correlations of -0.79, -0.82, and 0.74 with the 50-m and 200-m sprint times and the Margaria test, respectively. The data suggest that both the Wingate and isokinetic endurance tests represent valid laboratory tests for evaluating high-intensity, short-term exercise in which the muscle is primarily dependent upon anaerobic processes for energy release.     

Velocity specificity of weight training for kayak sprint performance

PURPOSE: Athletes often use weight training to prepare for sprint events, but the effectiveness of different types of weight training for sprinting is unclear. We have therefore investigated the effect of slow and explosive weight training on kayak sprint performance. METHODS: Twenty-seven male and 11 female experienced sprint kayakers were randomized to slow weight training, explosive weight training, or control (usual training) groups. Weight training consisted of two sessions per week for 6 wk; in each session the athletes performed 3-4 sets of two sport-specific exercises with a load of 80% 1-repetition-maximum. The two training programs differed only in the time taken to complete the concentric phase of the exercises: slow, 1.7 s; explosive, <0.85 s. To determine the effects of training on sprint acceleration and speed maintenance, the athletes performed 15-m kayaking sprints pre- and posttraining; an electronic timing system provided sprint times at 3.75-, 7.5-, and 15-m marks. RESULTS: Relative to control, both types of weight training substantially improved strength and sprint performance. The improvements in mean sprint time over 15 m in each group were: slow, 3.4%; explosive, 2.3%; control, -0.2% (90% confidence limits for pairwise differences, approximately +/-1.4%). Over the first 3.75 m, the improvements were: slow, 7.1%; explosive, 3.2%; control, 1.4% ( approximately +/-2.6%). Over the last 7.5 m, the improvements were: slow, 2.1%; explosive, 3.0%; control, -0.8% ( approximately +/-1.9%). CONCLUSIONS: Slow weight training is likely to be more effective than explosive training for improving the acceleration phase of sprinting, when force is high throughout the length of the stroke. Explosive weight training may be more effective in speed maintenance, when forces are developed rapidly over a short period at the start of the stroke.     

Application of force-velocity cycle ergometer test and vertical jump tests in the functional assessment of karate competitor

AIM: The aim of this study was to analyze the links between tests performances (vertical jump and force-velocity sprint on cycle ergometer) and 2 different karate level groups in order to propose a test battery adjusted to karate. METHODS: Twenty-two karate competitors (10 national junior team (IJ) and 12 national competition level (NL)) performed 4 maximal squat jumps (SJ), 4 maximal counter movement jumps (CMJ) on an ergojump and 3 8-s sprints on a friction braked cycle ergometer (friction loads of 0.5, 0.7, 0.9 N x kg(-1)). The maximal theoretical force (F(0)) and velocity (V(0)), the maximal power output (P(max)) and the optimal pedalling velocity (V(opt)) were derived from both the force -- velocity and the power -- velocity relationships plotted from all the 3 friction loads data. V(0), F(0), V(opt), P(max) and the best SJ and CMJ, were compared between IJ and NL groups. RESULTS: The IJ group was characterised by significantly higher values of V(0) (+13%) and SJ (+14.3%) compared to NL group, whereas no significant difference was observed between groups for F(0). Thus, karate performance would depend on maximal velocity and explosive strength. In addition, V(opt) was significantly higher in IJ group compared to NL group (135.4 rpm vs 119.2 rpm, p<0.001). Although based upon indirect evidence, these results accounted for mechanical functional capabilities of experts which could be particularly valuable when monitoring training of karate competitor. CONCLUSIONS: A force-velocity and a vertical jump tests may be applied in the functional assessment of karate competitor.     

Effect of load carriage on performance of an explosive, anaerobic military task

This study examined the effects of load carriage on performance of an explosive, anaerobic military task. A task-specific assessment requiring five 30-m timed sprints was developed to address this question. Seventeen soldiers (female = 5, male = 12) volunteered to undergo the test under two experimental conditions: unloaded (combat uniform and boots) and loaded (unloaded plus 21.6 kg fighting load, comprising webbing, weapon, helmet, and combat body armor). When loaded, there was a significant increase in the mean 30-m sprint time compared to unloaded (8.2 +/- 1.4 seconds vs. 6.2 +/- 0.8 seconds; p < 0.01). Of the total increase in mean sprint time, 51.7% occurred within the first 5 m. Female sprint times were affected to a larger extent than male (36% vs. 29%, respectively) as a result of the increased load. Fighting load significantly affected soldier mobility when conducting explosive, anaerobic military tasks, particularly among females, and specific physical conditioning should be considered to minimize this effect.     

Changes in selected biochemical, muscular strength, power, and endurance measures during deliberate overreaching and tapering in rugby league players

The purpose of this study was to examine the influence of overreaching on muscle strength, power, endurance and selected biochemical responses in rugby league players. Seven semi-professional rugby league players (.VO(2max) = 56.1 +/- 1.7 mL . kg (-1) . min (-1); age = 25.7 +/- 2.6 yr; BMI = 27.6 +/- 2.0) completed 6 weeks of progressive overload training with limited recovery periods. A short 7-day stepwise reduction taper immediately followed the overload period. Measures of muscular strength, power and endurance and selected biochemical parameters were taken before and after overload training and taper. Multistage fitness test running performance was significantly reduced (12.3 %) following the overload period. Although most other performance measures tended to decrease following the overload period, only peak hamstring torque at 1.05 rad . s (-1) was significantly reduced (p < 0.05). Following the taper, a significant increase in peak hamstring torque and isokinetic work at both slow (1.05 rad . s (-1)) and fast (5.25 rad . s (-1)) movement velocities were observed. Minimum clinically important performance decreases were measured in a multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) following the overload period. Following the taper, minimum clinically important increases in the multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) and 10-m sprint performance were observed. Compared to resting measures, the plasma testosterone to cortisol ratio, plasma glutamate, plasma glutamine to glutamate ratio and plasma creatine kinase activity demonstrated significant changes at the end of the overload training period (p < 0.05). These results suggest that muscular strength, power and endurance were reduced following the overload training, indicating a state of overreaching. The most likely explanation for the decreased performance is increased muscle damage via a decrease in the anabolic-catabolic balance.