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The prevalence of obesity continues to rise, and public health dietary recommendations are not being adhered to. The transition to higher education is a period of risk for weight gain in young adults and has been demonstrated as a good time to initiate behaviour change. A genotype‐based personalised approach to dietary recommendations may motivate young adults to maintain or adopt positive dietary behaviours. The aim of the present study was to determine the efficacy of genotype‐based personalised dietary and physical activity advice on healthy eating motivation in young adults. Participants were young adults (n = 153), aged 18–25 years. Baseline measures (participant characteristics, height, weight, body mass index [BMI], body fat percentage [BF%], healthy eating motivation and physical activity) were collected. Participants were genotyped for a SNP in the FTO gene (rs99396090) and randomly allocated (stratified for genotype) to three different groups (1. Genotype‐based personalised advice: dietary and physical activity advice based on genotype, BMI and reported physical activity; 2. Non‐genotype‐based personalised advice: dietary and physical activity advice based on BMI and reported physical activity; 3. Control: no advice). A week after receipt of advice delivered via email, participants completed the healthy eating motivation questionnaire for a second time. Genotype‐based personalised dietary advice did not affect healthy eating motivation: when participants were analysed across the whole group (p = 0.417), when analysed according to those informed of a risk or non‐risk‐associated genotype (p = 0.287), or when analysed according to those with a BMI (>25 kg/m2; p = 0.336) or BF% (male >18%, female >31%; p = 0.387) outside the healthy range. There was also no significant difference in healthy eating motivation at 1‐week in the control or non‐genotype‐based advice groups. Genotype‐based personalised advice for the prevention of obesity did not affect healthy eating motivation in this group of healthy, young adults. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of caffeine on heart rate and heart rate variability (HRV) at rest and during submaximal exercise. Using a balanced, double-blind, randomized, crossover design, 16 male cyclists (age: 37 ± 9 years; $\dot {\rm V}$V˙O2max: 4.44 ± 0.67 L·min−1) completed three trials in an air-conditioned laboratory. In Trial 1, cyclists completed two incremental cycling tests to establish the ${\dot {\rm V}}$V˙O2-power output relationship and $\dot {\rm V}$V˙O2max. In trials 2 and 3, cyclists were evaluated for heart rate and HRV at rest, after which they ingested a capsule containing 5 mg·kg−1 of caffeine or placebo. Thirty-five minutes post-supplementation, additional resting heart rate and HRV readings were taken after which cyclists completed a submaximal incremental cycling test (6 min stages) at 40–80% of ${\dot {\rm V}}$V˙O2max; with HR and HRV measurements taken in the last 5 min of each increment. HRV was determined from the root mean square of successive differences between R–R intervals. There were significant supplement × exercise intensity interactions on heart rate (p = .019) and HRV (p = .023), with post hoc tests on the latter showing that caffeine increased HRV at 40%, 50%, and 60% of ${\dot {\rm V}}$V˙O2max by 3.6 ± 4.9, 2.6 ± 2.8, and 0.6 ± 1.7 ms, respectively. There was a supplement × time interaction effect on resting HRV (p < .001), but not on heart rate (p = .351). The results of this study support the suggestion that caffeine increases the parasympathetic modulation of heart rate.Clinical trial registration number: NCT05521386. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the reliability of a single-trial determination of maximal accumulated oxygen deficit (MAOD) achieved via the aid of perceptually-regulated incremental exercise. Methods: 14 trained male cyclists (age: 45 ± 8 yrs; height: 1.82 ± 0.06 m; mass: 79.7 ± 6.7 kg; $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max : 4.09 ± 0.57 L·min−1) performed three trials of a submaximal incremental cycling test followed by a test to exhaustion at 116% of predicted $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max . The intensity for each stage of the incremental test was regulated by participants to elicit perceived exertion levels of 9–15 on the Borg (6–20) scale. Linear regression was used to estimate $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max at a perceived exertion level of 19. MAOD was calculated from the difference between predicted and actual oxygen demand in the test to exhaustion, reported in oxygen equivalents (O2 eq). A separate incremental test was used to measure $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max directly. Results: Correlation coefficients between perceived exertion and $${\dot{\rm{V}}{\rm{O}}_{2}}$$ V ˙ O 2 across trials were strong (r ≥0.99), and there were no between-trial differences in predicted $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max (4.03 ± 1.04, 3.76 ± 0.53, and 3.69 ± 0.64 L·min−1, respectively; p =.142) or MAOD (2.75 ± 2.28, 2.50 ± 1.53, and 2.93 ± 1.40 L O2 eq, respectively; p =.633). Nevertheless, the coefficients of variation for predicted $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max (14.2%) and MAOD (142.8%) were poor. Conclusions: The prediction of $${\dot{\rm{V}}{\rm{O}}_{2{\rm{max}}}}$$ V ˙ O 2 max from perceptually-regulated exercise displays a level of test-retest reliability which prevents its use as a means of evaluating MAOD reliably in a single-trial. [ABSTRACT FROM AUTHOR]

The aim of this study was to conduct a systematic review and meta-analysis of the effects of short-term creatine supplementation on repeated sprint ability. Fourteen studies met the inclusion criteria of adopting double-blind randomized placebo-controlled designs in which participants (age: 18–60 years) completed a repeated sprint test (number of sprints: 4 < n ≤ 20; sprint duration: ≤10 s; recovery duration: ≤90 s) before and after supplementing with creatine or placebo for 3–7 days in a dose of ∼20 g/day. No exclusion restrictions were placed on the mode of exercise. Meta-analyses were completed using random-effects models, with effects on measures of peak power output, mean power output, and fatigue (performance decline) during each repeated sprint test presented as standardized mean difference (δ), and with effects on body mass and posttest blood lactate concentration presented as raw mean difference (D). Relative to placebo, creatine resulted in a significant increase in body mass (D = 0.79 kg; p <.00001) and mean power output (δ = 0.61; p =.002). However, there was no effect of creatine on measures of peak power (δ = 0.41; p =.10), fatigue (δ = 0.08; p =.61), or posttest blood lactate concentration (D = 0.22 L/min; p =.60). In conclusion, creatine supplementation may increase mean power output during repeated sprint tests, although the absence of corresponding effects on peak power and fatigue means that more research, with measurements of intramuscular creatine content, is necessary to confirm. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the existence of the oxygen uptake (VO[subscript 2]) overshoot and the effects of exercise intensity and fitness status on the response during moderate-intensity exercise. Methods: Twelve "high-fitness" (M[subscript age] = 26 ± 5 years; M[subscript height] = 184.1 ± 5.4 cm; M[subscript body mass] = 76.6 ± 8.9 kg; mean peak oxygen uptake (VO[subscript 2]peak) = 59.0 ± 3.3 mL·kg[superscript -1]·min·[superscript -1]) and 11 "moderate-fitness" (M[subscript age] = 29 ± 5 years; M[subscript height] = 178.7 ± 7.5 cm; M[subscript body mass] = 81.7 ± 10.9 kg; MV?O[subscript 2]peak = 45.2 ± 3.1 mL·kg[superscript -1]·min·[superscript -1]) participants performed square-wave transitions from unloaded cycling to 3 different intensities (70%, 82.5%, and 95% of the gas exchange threshold). The data were modeled using both a mono-exponential function (Model 1) and a function that included a switch-on component (Model 2). The overshoot was computed by subtracting the steady state from the peak of the modeled response and by calculating the area of the curve that was above steady state. Results: The goodness of fit was affected by model type (p = 0.002) and exercise intensity (p < 0.001). High-fitness participants displayed a smaller t (p < 0.05) and a larger amplitude (p < 0.05) and were more likely to overshoot the steady state (p = 0.035). However, while exercise intensity did affect the amplitude (p < 0.001), it did not affect t (p = 0.05) or the likelihood of an overshoot occurring (p = 0.389). Conclusion: While exercise intensity did not alter the VO[subscript 2] response, fitness status affected t and the likelihood of an overshoot occurring. The overshoot questions the traditional approach to modeling moderate-intensity VO[subscript 2] data.

Purpose: To investigate the influence of torque factor and sprint duration on the effects of caffeine on sprint cycling performance. Methods: Using a counterbalanced, randomized, double-blind, placebo-controlled design, 13 men completed 9 trials. In trial 1, participants completed a series of 6-s sprints at increasing torque factors to determine the torque factor, for each individual, that elicited the highest (Toptimal) peak power output (PPO). The remaining trials involved all combinations of torque factor (0.8 N·m−1·kg−1 vs Toptimal), sprint duration (10 s vs 30 s), and supplementation (caffeine [5 mg·kg−1] vs placebo). Results: There was a significant effect of torque factor on PPO, with higher values at Toptimal (mean difference 168 W; 95% likely range 142–195 W). There was also a significant effect of sprint duration on PPO, with higher values in 10-s sprints (mean difference 52 W; 95% likely range 18–86 W). However, there was no effect of supplementation on PPO (P =.056). Nevertheless, there was a significant torque factor × sprint duration × supplement interaction (P =.036), with post hoc tests revealing that caffeine produced a higher PPO (mean difference 76 W; 95% likely range 19–133 W) when the sprint duration was 10 s and the torque factor was Toptimal. Conclusion: The results of this study show that when torque factor and sprint duration are optimized, to allow participants to express their highest PPO, there is a clear effect of caffeine on sprinting performance. [ABSTRACT FROM AUTHOR]

The aim of this study was to carry out a systematic review and meta-analysis of the effects of caffeine supplementation on physiological responses to submaximal exercise. A total of 26 studies met the inclusion criteria of adopting double-blind, randomized crossover designs that included a sustained (5-30 min) fixed-intensity bout of submaximal exercise (constrained to 60-85% maximal rate of oxygen consumption) using a standard caffeine dose of 3-6 mg⋅kg-1 administered 30-90 min prior to exercise. Meta-analyses were completed using a random-effects model, and data are presented as raw mean difference (D) with associated 95% confidence limits (CLs). Relative to placebo, caffeine led to significant increases in submaximal measures of minute ventilation (D = 3.36 L⋅min-1; 95% CL, 1.63-5.08; P = .0001; n = 73), blood lactate (D = 0.69 mmol⋅L-1; 95% CL, 0.46- 0.93; P < .00001; n = 208), and blood glucose (D = 0.42 mmol⋅L-1; 95% CL, 0.29-0.55; P < .00001; n = 129). In contrast, caffeine had a suppressive effect on ratings of perceived exertion (D = -0.8; 95% CL, -1.1 to -0.6; P < .00001; n = 147). Caffeine had no effect on measures of heart rate (P = .99; n = 207), respiratory exchange ratio (P = .18; n = 181), or oxygen consumption (P = .92; n = 203). The positive effects of caffeine supplementation on sustained high-intensity exercise performance are widely accepted, although the mechanisms to explain that response are currently unresolved. This meta-analysis has revealed clear effects of caffeine on various physiological responses during submaximal exercise, which may help explain its ergogenic action. [ABSTRACT FROM AUTHOR]

Background: Dietary intake is linked to numerous modifiable risk factors of cardiovascular disease. Current dietary recommendations in the UK to reduce the risk of cardiovascular disease are not being met. A genotype-based personalised approach to dietary recommendations may motivate individuals to make positive changes in their dietary behaviour. Aim: To determine the effect of a personalised nutrition intervention, based on apolipoprotein E (ApoE, rs7412; rs429358) and methylenetetrahydrofolate reductase (MTHFR, rs1801133) genotype, on reported dietary intake of saturated fat and folate in participants informed of a risk genotype compared to those informed of non-risk genotype. Methods: Baseline data (n = 99) were collected to determine genotype (non-risk vs risk), dietary intake and cardiovascular risk (Q-Risk®2 cardiovascular risk calculator). Participants were provided with personalised nutrition advice via email based on their ApoE and MTHFR genotype and reported intake of folate and saturated fat. After 10 days, dietary intake data were reported for a second time. Results: Personalised nutrition advice led to favourable dietary changes, irrespective of genotype, in participants who were not meeting dietary recommendations at baseline for saturated fat (p < 0.001) and folate (p = 0.002). Only participants who were informed of a risk ApoE genotype met saturated fat recommendations following personalised nutrition advice. Conclusion: Incorporation of genotype-based personalised nutrition advice in a diet behaviour intervention may elicit favourable changes in dietary behaviour in participants informed of a risk genotype. Participants informed of a non-risk genotype also respond to personalised nutrition advice favourably but to a lesser extent. [ABSTRACT FROM AUTHOR]

Glaister, M, Witmer, C, Clarke, DW, Guers, JJ, Heller, JL, and Moir, GL. Familiarization, reliability, and evaluation of a multiple sprint running test using self-selected recovery periods. J Strength Cond Res 24(12): 3296-3301, 2010-The aims of the present study were to investigate the process of self-selected recovery in a multiple sprint test with a view to using self-selected recovery time as a means of reliably quantifying an individual's ability to resist fatigue in this type of exercise. Twenty physically active exercise science students (means [+ or -] SD for age, height, body mass, body fat, and [??][O.sub.2] max of the subjects were 21 [+ or -] 2 yr, 1.79 [+ or -] 0.09 m, 83.7 [+ or -] 10.8 kg, 16.6 [+ or -] 3.9%, and 52.7 [+ or -] 7.2 ml*[kg.sup.-1]*[min.sup.-1], respectively) completed 4 trials of a 12 x 30 m multiple sprint running test under the instruction that they should allow sufficient recovery time between sprints to enable maximal sprint performance to be maintained throughout each trial. Mean recovery times across the 4 trials were 73.9 [+ or -] 24.7, 82.3 [+ or -] 23.8, 77.6 [+ or -] 19.1, and 77.5 [+ or -] 13.9 seconds, respectively, with variability across the first 3 trials considered evidence of learning effects. Test-retest reliability across trials 3 to 4 revealed a good level of reliability as evidenced by a coefficient of variation of 11.1% (95% likely range: 8.0-18.1%) and an intraclass correlation coefficient of 0.76 (95% likely range: 0.40-0.91). Despite no change in sprint performance throughout the trials, ratings of perceived exertion increased progressively and significantly (p < 0.001) from a value of 10 [+ or -] 2 after sprint 3 to 14 [+ or -] 2 after sprint 12. The correlation between relative V[O.sub.2] max and mean recovery time was 0.14 (95% likely range: -0.37-0.58). The results of the present study show that after the completion of 2 familiarization trials, the ability to maintain sprinting performance in a series of repeated sprints can be self-regulated by an athlete to a high degree of accuracy without the need for external timepieces. KEY WORDS repeated sprint ability, intermittent, perceived recovery, multiple sprint work

The purpose of this study was to examine the effect of work-interval duration (WlD) and intensity on the time spent at, or above, 95% [Vo.sub.2]max (T95 [Vo.sub.2]max) during intermittent bouts of supramaximal exercise. Over a 5-week period, 7 physically active men with a mean ([+ or -] SD) age, height, body mass, and [Vo.sub.2]max of 22 [+ or -] 5 years, 181.5 [+ or -] 5.6 cm, 86.4 [+ or -] 11.4 kg, and 51.5 [+ or -] 1.5 ml*[kg.sup.-1][min.sup.-1], respectively, attended 7 testing sessions. After completing a submaximal incremental test on a treadmill to identify individual oxygen uptake/running velocity relationships, subjects completed a maximal incremental test to exhaustion to establish [Vo.sub.2]max and subsequently (from the aforementioned relationship) the minimum velocity required to elicit [Vo.sub.2]max (v[Vo.sub.2]max). In a random order, subjects then carried out 3 intermittent runs to exhaustion at both 105% and 115% v[Vo.sub.2]max. Each test used a different WlD (20 s, 25 s, or 30 s) interspersed with 20-second passive recovery periods. Results revealed no significant difference in T95 [vVo.sub.2]max for intermittent runs at 105% versus 115% [vVo.sub.2]max (p = 0.142). There was, however, a significant effect (p < 0.001) of WID on T95 [Vo.sub.2]max, with WlDs of 30 seconds enabling more time relative to WlDs of 20 seconds (p = 0.018) and 25 seconds (p = 0.009). Moreover, there was an interaction between intensity and duration such that the effect of WID was magnified at the lower exercise intensity (p = 0.046). In conclusion, despite a number of limitations, the results of this investigation suggest that exercise intensities of approximately 105% [vVo.sub.2]max combined with WlDs greater than 25 seconds provide the best way of optimizing T95 [Vo.sub.2]max when using fixed 20-second stationary rest periods. KEY WORDS maximal aerobic capacityi endurance running performance, interval training

The ability to repeatedly produce a high-power output or sprint speed is a key fitness component of most field and court sports. The aim of this study was to evaluate the validity and reliability of eight different approaches to quantify this parameter in tests of multiple-sprint performance. Ten physically active men completed two trials of each of two multiplesprint running protocols with contrasting recovery periods. Protocol 1 consisted of 12 x 30-m sprints repeated every 35 seconds; protocol 2 consisted of 12 x 30-m sprints repeated every 65 seconds. All testing was performed in an indoor sports facility, and sprint times were recorded using twin-beam photocells. All but one of the formulae showed good construct validity, as evidenced by similar within-protocol fatigue scores. However, the assumptions on which many of the formulae were based, combined with poor or inconsistent test-retest reliability (coefficient of variation range: 0.8-145.7%; intraclass correlation coefficient range: 0.09-0.75), suggested many problems regarding logical validity. In line with previous research, the results support the percentage decrement calculation as the most valid and reliable method of quantifying fatigue in tests of multiple-sprint performance.

The aims of this study were to examine (a) the relationship between maximal oxygen uptake ([Vo.sub.2]max) and several performance indices of multiple sprint cycling; (b) the relationship between maximal accumulated oxygen deficit (MAOD) and those same performance indices; and (c) the influence of recovery duration on the magnitude of those relationships. Twenty-five physically active men completed a [Vo.sub.2]max test, a MAOD test, and 2 maximal intermittent (20 x 5 seconds) sprint cycling tests with contrasting recovery periods (10 seconds or 30 seconds). Mean [+ or -] SD for age, height, and body mass were 20.6 [+ or -] 1.5 years, 177.2 [+ or -] 5.4 cm, and 78.2 [+ or -] 8.2 kg, respectively. All tests were conducted on a friction-braked cycle ergometer with subsequent data normalized for body mass. Moderate (0.3 [less than or equal to] r < 0.5) positive correlations were observed between power output data and MAOD (range, 0.31-0.46; 95% confidence limits, -0.10 to 0.72). Moderate to large positive correlations also were observed between power output data and [Vo.sub.2]max, the magnitude of which increased as values were averaged across all sprints (range, 0.45-0.67; 95% confidence limits 0.07-0.84). Correlations between fatigue and [Vo.sub.2]max were greater in the intermittent protocol with 30-second recovery periods (r = -0.34; 95% confidence limits, 0.06 to -0.65). The results of this study reflect the complex energetics associated with multiple sprint work. Though the findings add support to the idea that multiple sprint sports demand a combination of speed and endurance, further longitudinal research is required to confirm the relative importance of these parameters. KEY WORDS. correlation, intermittent exercise, repeated bouts, performance indices

The aim of this study was to examine the effects of short-term creatine monohydrate supplementation on multiple sprint running performance. Using a double-blind research design, 42 physically active men completed a series of 3 indoor multiple sprint running trials (15 x 30 m repeated at 35-second intervals). After the first 2 trials (familiarization and baseline), subjects were matched for fatigue score before being randomly assigned to 5 days of either creatine (4 x [d.sup.-1] x 5 g creatine monohydrate + 1 g maltodextrin) or placebo (4 x [d.sup.-1] x 6 g maltodextrin) supplementation. Sprint times were recorded via twin-beam photocells, and earlobe blood samples were drawn to evaluate posttest lactate concentrations. Relative to placebo, creatine supplementation resulted in a 0.7 kg increase in body mass (95% likely range: 0.02 to 1.3 kg) and a 0.4% reduction in body fat (95% likely range: -0.2 to 0.9%). There were no significant (p > 0.05) between-group differences in multiple sprint measures of fastest time, mean time, fatigue, or posttest blood lactate concentration. Despite widespread use as an ergogenic aid in sport, the results of this study suggest that creatine monohydrate supplementation conveys no benefit to multiple sprint running performance. KEY WORDS. intermittent ergogenic aid, repeated sprint, fatigue

Purpose: The aim of the study was to determine the effect of supramaximal exercise intensity during constant work-rate cycling to exhaustion on the accumulated oxygen deficit (AOD) and to determine the test--retest reliability of AOD. Methods: Twenty-one trained male cyclists and triathletes (mean ± SD for age and maximal oxygen uptake [...O2max] were 41 ± 7 y and 4.53 ± 0.54 L/min, respectively) performed initial tests to determine the linear relationship between ...O2 and power output, and ...O2max. In subsequent trials, AOD was determined from exhaustive square-wave cycling trials at 105%, 112.5% (in duplicate), 120%, and 127.5% ...O2max. Results: Exercise intensity had an effect (P = .011) on the AOD (3.84 ± 1.11, 4.23 ± 0.96, 4.09 ± 0.87, and 3.93 ± 0.89 L at 105%, 112.5%, 120%, and 127.5% ...O2max, respectively). Specifically, AOD at 112.5% ...O2max was greater than at 105% ...O2max (P = .033) and at 127.5% ...O2max (P = .022), but there were no differences between the AOD at 112.5% and 120% ...O2max. In 76% of the participants, the maximal AOD occurred at 112.5% or 120% ...O2max. The reliability statistics of the AOD at 112.5% ...O2max, determined as intraclass correlation coefficient and coefficient of variation, were .927 and 8.72%, respectively. Conclusions: The AOD, determined from square-wave cycling bouts to exhaustion, peaks at intensities of 112.5-120% ...O2max. Moreover, the AOD at 112.5% ...O2max exhibits an 8.72% test--retest reliability. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the influence of recovery duration on various measures of multiple sprint cycling performance. Twenty-five physically active men completed 2 maximal multiple sprint (20 x 5 seconds) cycling tests with contrasting recovery periods (10 or 30 seconds). The mean [+ or -] SD values for age, height, and body mass were 20.6 [+ or -] 1.5 years, 177.2 [+ or -] 5.4 cm, and 78.2 [+ or -] 8.2 kg, respectively. All tests were conducted on a friction-braked cycle ergometer. Longer (30 seconds) recovery periods resulted in significantly (p < 0.05) higher measures of maximum (~4%) and mean (~26%) power output, the former appearing to result from a potentiation effect during the first few sprints. Thirty-second recovery periods also corresponded with significantly lower measures of fatigue (absolute difference: 16.1%; 95% likely range: 14.1-18.2%), heart rate, respiratory exchange ratio, and oxygen uptake. Blood lactate and ratings of perceived exertion (6-20 scale) increased progressively throughout both protocols and were significantly lower with 30-second recovery periods. The results of this study illustrate the considerable influence of recovery duration on various measures of multiple sprint work. Although the precise mechanisms of this response require further investigation, coaches and sport scientists should consider these findings when attempting to develop or evaluate the performance capabilities of athletes involved in multiple sprint sports. Key Words. intermittent exercise, power output, repeated sprint, recovery

Moir, G., R. Sanders, C. Button, and M. Glaister. The influence of familiarization on the reliability of force variables measured during unloaded and loaded vertical jumps. J. Strength Cond. Res. 19(1):140-145. 2005.--The purpose of this study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with force variables recorded during unloaded and loaded (30 and 60% of 1 repetition maximum squat [1RM]) static vertical jumps (SJ). Nine physically active men attended 4 separate testing sessions over a 2-week period. Force platform recordings of peak force, peak rate of force development (pRFD), average rate of force development, takeoff velocity, average power, and peak power were obtained for each jump. During each of the 4 testing sessions, 3 jumps were performed under each of the load conditions. The average of the force variables were used in the analysis. Familiarization was assessed using the scores obtained during the 4 separate testing sessions. Reliability was assessed by calculating intraclass correlation coefficients (ICCs) and coefficient of variation (CV) associated with the force variables. No significant differences (p > 0.05) were obtained between the testing sessions for any of the force variables. With the exception of pRFD, the force variables showed reasonably good levels of test-retest reliability (ICC range: 0.75-0.99; CV range: 1.2-7.6%). High levels of reliability can be achieved in a variety of force variables without the need for familiarization sessions when performing SJ under unloaded conditions and with loads of 30 and 60% of 1RM squat with physically active men. KEY WORDS. static jumps, force platform, reliability, familiarization

The purpose of the present study was to assess the reliability and validity of fatigue measures, as derived from 4 separate formulae, during tests of repeat sprint ability. On separate days over a 3-week period, 2 groups of 7 recreationally active men completed 6 trials of 1 of 2 maximal (20 x 5 seconds) intermittent cycling tests with contrasting recovery periods (10 or 30 seconds). All trials were conducted on a friction-braked cycle ergometer, and fatigue scores were derived from measures of mean power output for each sprint. Apart from formula 1, which calculated fatigue from the percentage difference in mean power output between the first and last sprint, all remaining formulae produced fatigue scores that showed a reasonably good level of test-retest reliability in both intermittent test protocols (intraclass correlation range: 0.78-0.86; 95% likely range of true values: 0.54-0.97). Although between-protocol differences in the magnitude of the fatigue scores suggested good construct validity, within-protocol differences highlighted limitations with each formula. Overall, the results support the use of the percentage decrement score as the most valid and reliable measure of fatigue during brief maximal intermittent work. KEY WORDS. reliability, multiple sprints, intermittent exercise

The purpose of the present study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with loaded vertical jump and 20-m sprint running performance. Ten physically active men attended 5 separate testing sessions over a 3-week period where they performed unloaded and loaded (10-kg extra load) countermovement (CMJ) and static (SJ) jumps, followed by straight-line 20-m sprints. Jump height was recorded for the vertical jumps using a jump mat, while the time for 10 m and 20 m was recorded during the sprints using photocells. The highest (jump conditions) and fastest (sprint) of 3 trials performed during each of the 5 testing sessions was used in the subsequent analysis. Familiarization was assessed using the scores obtained during the 5 separate testing sessions. Reliability was assessed by calculating intraclass correlation coefficients (ICCs) and coefficient of variation (CV). No significant differences were obtained between the testing sessions for any of the measures. ICCs ranged from 0.89 to 0.95, while CVs ranged from 1.9 to 2.6%. These results indicate that high levels of reliability can be achieved without the need for familiarization sessions when using loaded and unloaded CMJ and SJ and 20-m sprint performance with physically active men. KEY WORDS. vertical jump, sprinting, reproducibility, learning

The aims of the present study were: (a) to determine the number of familiarization trials required to establish a high degree of reliability in measures of power output during maximal intermittent cycling; and (b) to examine the reliability of those same measures after familiarization had been established. On separate days over a 3-week period, 2 groups of 7 recreationally active men completed 8 trials of 1 of 2 maximal (20 x 5-second) intermittent cycling tests with contrasting recovery periods (10-seconds or 30-seconds). Significant (p < 0.05) between-trial differences were detected in post-hoc tests involving trials 1 and 2 only. Within-subject test-retest reliability was therefore assessed across trials 3-8. Apart from values of maximum power output in Protocol 1 (10-second recovery periods), all remaining measures of power output showed high degrees of within-subject test-retest reliability (coefficient of variation: 2.4-3.7%). The results of the present study indicate that in subjects unfamiliar with maximal intermittent cycling, high degrees of reliability in many performance measures can be achieved following the completion of 2 familiarization trials. Key Words: familiarization, test-retest reliability, multiple sprints, intermittent exercise