The effects of work:rest duration on physiological and perceptual responses during intermittent exercise and performance

Abstract

In this study, we examined the effects of different work:rest durations during 20 min intermittent treadmill running and subsequent performance. Nine males (mean age 25.8 years, s = 6.8; body mass 73.9 kg, s = 8.8; stature 1.75 m, s = 0.05; [Vdot]O_2max 55.5 ml · kg^?1 · min^?1, s = 5.8) undertook repeated sprints at 120% of the speed at which [Vdot]O_2max was attained interspersed with passive recovery. The work:rest ratio was constant (1:1.5) with trials involving either short (6:9 s) or long (24:36 s) work:rest exercise protocols (total exercise time 8 min). Each trial was followed by a performance run to volitional exhaustion at the same running speed. Testing order was randomized and counterbalanced. Heart rate, oxygen consumption, respiratory exchange ratio, and blood glucose were similar between trials (P > 0.05). Blood lactate concentration was greater during the long than the short exercise protocol (P < 0.05), whereas blood pH was lower during the long than the short exercise protocol (7.28, s = 0.11 and 7.30, s = 0.03 at 20 min, respectively; P < 0.05). Perceptions of effort were greater throughout exercise for the long than the short exercise protocol (16.6, s = 1.4 and 15.1, s = 1.6 at 20 min, respectively; P < 0.05) and correlated with blood lactate (r = 0.43) and bicarbonate concentrations (r = ?0.59; P < 0.05). Although blood lactate concentration at 20 min was related to performance time (r = ?0.56; P < 0.05), no differences were observed between trials for time to exhaustion (short exercise protocol: 95.8 s, s = 30.0; long exercise protocol: 92.0 s, s = 37.1) or physiological responses at exhaustion (P > 0.05). Our results demonstrate that 20 min of intermittent exercise involving a long work:rest duration elicits greater metabolic and perceptual strain than intermittent exercise undertaken with a short work:rest duration but does not affect subsequent run time to exhaustion.     

Effects of a cooling collar on affect,ratings of perceived exertion,and running performance in the heat

Abstract

During prolonged exercise, ratings of perceived exertion (RPE) and affect (pleasure; activation) play an important role in performance, especially in hot conditions. Although various mechanisms have been tried to manage the effects of heat (e.g. cooling jackets), the purpose of the current research was to assess the effect of a cooling collar on RPE, affect, thermal sensation, and running performance in the heat. Participants (n =8) wore a cold collar, uncooled collar or no collar as they completed three 90-min preloaded treadmill time-trials in the heat (30.5±0.1°C), which included 75 min at ～60% [Vdot]O_2max followed by a 15-min time-trial. Affect, RPE, and thermal sensation were measured throughout. Performance during the time-trial was significantly improved in the cold collar compared with the uncooled collar and no-collar trials; however, pleasure and activation ratings were highest for the no-collar trial. Findings suggest that a cooling collar may improve performance, but not necessarily “feel good”. Practically, it seems necessary to ensure sufficient education about the benefits, on balance, of the cold collar, while the performance improvements outweighed the reported discomfort of athletes in this study. In addition, the cold collar may prove quite beneficial for individuals who work in hot climates and or conditions, as it may be effective in minimizing discomfort associated with heat for other groups as well.     

Activity profile and physiological demands of top-class soccer assistant refereeing in relation to training status

To determine the movement patterns and physiological demands of top-class soccer assistant referees, we performed computerized time-motion analysis and measured heart rate and blood lactate concentration in 15 assistant referees during 22 competitive matches in the top Danish league. To relate match performance to the physical capability of the assistant referees, they performed a 3 2 30 m sprint protocol before and after matches and a laboratory treadmill test within 3 weeks of the games. The mean total distance covered by the top-class assistant referees was 7.28 (range 5.78-8.16) km, of which 1.15 (0.86-1.44) km was high-intensity running and 1.16 (0.12-2.34) km was sideways running. The amount of high-intensity running during a game was correlated with performance of repeated sprints (r = 0.80, P ? 0.05). Mean heart rate was 137 (117-159) beats · min^-1 , corresponding to 73% (60-88%) of maximal heart rate and 65% (53-80%) of maximal oxygen uptake. Blood lactate concentration was 4.7 (1.6-11.0) and 4.8 (1.1-13.7) mmol · l -1 after the first and second half, respectively. Sprinting performance was poorer (P ? 0.05) after than before the games. The peak distance to the offside line was greater (P ? 0.05) in the second than the first half (7 - 1 vs 5 - 0 m). Our results show that: (1) top-class assistant soccer refereeing is characterized by brief intense bouts of forward and sideways running interspersed with long periods of low activity; (2) top-class soccer assistant referees have moderate aerobic energy production during games with episodes of high aerobic and anaerobic energy turnover; (3) assistant referees' performance of repeated sprints correlates with the amount of high-intensity running performed in a game; and (4) sprint performance decreases towards the end of a game, which appears to affect assistant referees' ability to keep up with play.     

The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise

Abstract

The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1±503.5 and 5696.7±530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5–91.5% HR_max. Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions. The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.     

Effects of Altered Stride Lengths on Ratings of Perceived Exertion during Running

Abstract

The purpose of this study was to determine the effects of stride length variations on ratings of perceived exertion (RPEs) in experienced recreational runners. Twenty-eight male college students were randomly divided into equal-sized treatment and control groups. The treatment group performed five 15 min altered stride length runs, each separated by a minimum of 48 hr. The five trials involved running with a freely chosen stride length (FCSL) and a FCSL altered by +14%, +7%, ?14%, and ?7%. The control group was utilized to monitor changes in subjects' RPEs as a result of practice effects developed through repeated bouts of treadmill running. Results revealed that the treatment group's local and general RPEs for the over striding runs (+14%, +7%) were significantly greater (p < .01) than RPEs recorded during the FCSL run. Additionally, there was a marginally significant difference (p < .05) in local RPEs between the FCSL run and the extreme understriding run (?14%). Analysis of variance on the control group's RPE data suggests that neither local nor general RPEs changed significantly in repeated FCSL runs across the six-week testing period. The results of this study suggest that experienced recreational runners perceive differences in exertion accompanying changes in stride length.     

The influence of core affect on cyclo-ergometer endurance performance: Effects on performance outcomes and perceived exertion

BackgroundCore affect is defined as the most general affective construct consciously accessible that is experienced constantly. It can be experienced as free-floating (mood) or related to prototypical emotional episodes. The aim of this study was to examine the influence of pleasant and unpleasant core affect on cyclo-ergometer endurance performance. Specifically, we considered the influence of pleasant and unpleasant core affect on performance outcomes (i.e., time to task completion) and rate of perceived exertion (RPE; Borg Scale, category ratio-10) collected during the task.MethodsThirty-one participants aged 20–28 years were recruited. Core affect was randomly elicited by 2 sets of pleasant and unpleasant pictures chosen from the international affective picture system. Pictures were displayed to participants during a cyclo-ergometer performance in 2 days in a counterbalanced order. RPE was collected every minute to detect volunteers’ exhaustion.ResultsThe study sample was split into 2 groups. Group 1 comprised participants who performed better with pleasant core affect, whereas Group 2 included participants who performed better with unpleasant core affect. Mixed between-within subjects analysis of variance revealed a significant 2 (group) × 2 (condition) × 5 (isotime) interaction (p = 0.002, η_p² = 0.158). Post hoc comparisons showed that participants who obtained better performance with pleasant core affect (pleasant pictures; Group 1) reported lower RPE values at 75% of time to exhaustion in a pleasant core affect condition compared to an unpleasant core affect condition. On the other hand, participants who obtained better performance with unpleasant core affect (unpleasant pictures; Group 2) reported lower RPE values at 75% and 100% of time to exhaustion in an unpleasant core affect condition.ConclusionFindings suggest differential effects of pleasant and unpleasant core affect on performance. Moreover, core affect was found to influence perceived exertion and performance according to participants’ preferences for pleasant or unpleasant core affect.     

Effect of a Brazilian Jiu-jitsu-simulated tournament on strength parameters and perceptual responses

This study aimed to analyse the effects of a simulated Brazilian jiu-jitsu (BJJ) tournament on vertical jump performance, grip strength test and perceived effort responses. 22 male BJJ athletes participated in a simulated tournament consisting of three 7 min matches separated by 14 min of rest. Kimono grip strength test (KGST), counter movement jump (CMJ) and rate of perceived exertion (RPE) were measured before and after each match, while RPE of specific areas was assessed after three matches. ANOVA for repeated measures was used to compare strength parameters after each match with the level of significance set at 5%. The key results showed a significant decrease of jump height (p = 0.001) and net vertical impulse in the CMJ (p = 0.031), as well as a reduction of the number of reps in the KGST (p < 0.001). A significant increase of RPE was found throughout the matches (p < 0.001). Considering the RPE in specific areas, no differences were observed between the upper and lower body (p = 0.743). We conclude that the BJJ simulated tournament generated a decrease of performance in both upper and lower limbs and provoked a progressive increase in the effort perception over the matches.     

丙酮酸或丙酮酸-肉碱补充对定量负荷运动时脂肪动用和RPE的影响

本研究通过观察定量负待运动前后血液中自由脂肪酸、血糖和乳酸水平的变化及运动中RQ和RPE的变化，研究丙酮改补充对机体有氧运动时脂肪动用和主观感觉疲劳的影响及肉碱对此的作用，探讨丙酮酸—肉碱复合剂的应用价值。结果：与安慰剂组相比，2试验组的FFA水平较高；除定量负荷运动30mi时外，丙酮酸组在安静时，定量负荷运动15min时的RQ较低，复合剂组在各种条件下的RQ均较低，2试验组运动中RPE较低，均有显著性意义。结论：丙酮酸补充能促进有氧运动中脂肪的动员，但对有氧运动中脂肪利用的影响不大；复合剂能同时促进有氧运动中脂肪的动员和利用；丙酮酸和复合剂能改善有氧运动时的主观感觉疲劳状态；复合剂对体重控制有一定的应用价值。     

The effect of recovery duration on running speed and stroke quality during intermittent training drills in elite tennis players

The aim of this study was to assess the effect of the recovery duration in intermittent training drills on metabolism and coordination in sport games. Ten nationally ranked male tennis players (age 25.3±3.7 years, height 1.83±0.8 m, body mass 77.8±7.7 kg; mean ±s _x ) participated in a passing-shot drill (baseline sprint with subsequent passing shot) that aimed to improve both starting speed and stroke quality (speed and precision). Time pressure for stroke preparation was individually adjusted by a ball-machine and corresponded to 80% of maximum running speed. In two trials (T₁₀, T₁₅) separated by 2 weeks, the players completed 30 strokes and sprints subdivided into 6 2 5 repetitions with a 1 min rest between series. The rest between each stroke-and-sprint lasted either 10 s (T₁₀) or 15 s (T₁₅). The sequence of both conditions was randomized between participants. Post-exercise blood lactate concentration was significantly elevated in T₁₀ (9.04±3.06 vs 5.01±1.35 mmol·l^-1, P ? 0.01). Running time for stroke preparation (1.405±0.044 vs 1.376±0.045 s, P ? 0.05) and stroke speed (106±12 vs 114±8 km·h^-1, P ? 0.05) were significantly decreased in T₁₀, while stroke precision - that is, more target hits ( P ? 0.1) and fewer errors (P ? 0.05) - tended to be higher. We conclude that running speed and stroke quality during intermittent tennis drills are highly dependent on the duration of recovery time. Optimization of training efficacy in sport games (e.g. combined improvement of conditional and technical skills) requires skilful fine-tuning of monitoring guidelines.     

The influence of playing surface on physiological and performance responses during and after soccer simulation

The aim of this study was to investigate the effect of playing surface on physiological and performance responses during and in the 48 h after simulated soccer match play. Blood lactate, single-sprint, repeated-sprint and agility of eight amateur soccer players were assessed throughout a 90-min soccer-simulation protocol (SSP) completed on natural turf (NT) and artificial turf. Counter-movement jump, multiple-rebound jump, sprint (10 m, 60 m), L-agility run (L-AR), creatine kinase (CK) and perception of muscle soreness (PMS) were measured before, immediately after, 24 h and 48 h after exercise. Analyses revealed significant changes in blood lactate and single-sprint performance (both P < 0.05) during the SSP but with no significant differences between surfaces. Conversely, repeated-sprint performance demonstrated an interaction effect, with reductions in performance evident on NT only (P < 0.05). Whilst L-AR and 10-m sprint performance remained unchanged, 60-m sprint and multiple-rebound jump performance were impaired, and PMS and CK were elevated immediately following the SSP (all P < 0.05) but with no surface effects. Although performance, CK and PMS were negatively affected to some degree in the 48 h after the SSP, there was no surface effect. For the artificial and natural surfaces used in the present study, physiological and performance responses to simulated soccer match play appear to be similar. Whilst a potential for small differences in performance response exists during activity, surface type does not affect the pattern of recovery following simulated match play.     

Effects of active,passive or no warm-up on metabolism and performance during high-intensity exercise

The aim of this study was to determine the influence of type of warm-up on metabolism and performance during high-intensity exercise. Eight males performed 30 s of intense exercise at 120% of their maximal power output followed, 1 min later, by a performance cycle to exhaustion, again at 120% of maximal power output. Exercise was preceded by active, passive or no warm-up (control). Muscle temperature, immediately before exercise, was significantly elevated after active and passive warm-ups compared to the control condition (36.9 - 0.18°C, 36.8 - 0.18°C and 33.6 - 0.25°C respectively; mean - sx ) ( P ? 0.05). Total oxygen consumption during the 30 s exercise bout was significantly greater in the active and passive warm-up trials than in the control trial (1017 - 22, 943 - 53 and 838 - 45 ml O 2 respectively). Active warm-up resulted in a blunted blood lactate response during high-intensity exercise compared to the passive and control trials (change = 5.53 - 0.52, 8.09 - 0.57 and 7.90 - 0.38 mmol· l -1 respectively) ( P ? 0.05). There was no difference in exercise time to exhaustion between the active, passive and control trials (43.9 - 4.1, 48.3 - 2.7 and 46.9 - 6.2 s respectively) ( P = 0.69). These results indicate that, although the mechanism by which muscle temperature is elevated influences certain metabolic responses during subsequent high-intensity exercise, cycling performance is not significantly affected.     

The effects of arm crank strategy on physiological responses and mechanical efficiency during submaximal exercise

Abstract

The purpose of this study was to compare submaximal physiological responses and indices of mechanical efficiency between asynchronous and synchronous arm ergometry. Thirteen wheelchair-dependent trained athletes performed eight steady-state incremental bouts of exercise (0 to 140 W), each lasting 4 min, using synchronous and asynchronous arm-cranking strategies. Physiological measures included oxygen uptake ([Vdot]O₂), heart rate, and blood lactate concentration. The power outputs corresponding to fixed whole blood lactate concentrations of 2.0 to 4.0 mmol · l^?1 were calculated using linear interpolation. Mechanical efficiency indices – gross efficiency, net efficiency, and work efficiency – were also calculated. An analysis of variance with repeated measures was applied to determine the effect of crank mode on the physiological parameters. Oxygen uptake was on average 10% lower (P < 0.01), and both net efficiency (P < 0.01) and gross efficiency (P < 0.01) were higher, during the asynchronous strategy at both 60 and 80 W (gross efficiency: 16.9 ± 2.0% vs. 14.7 ± 2.4% and 17.5 ± 1.8% vs. 15.9 ± 2.6% at 60 and 80 W respectively). There were no differences in heart rate, blood lactate concentration or power output at either of the blood lactate reference points between the asynchronous and synchronous strategies (P > 0.05). In conclusion, test specificity is an important consideration. If a synchronous strategy is to be adopted, it is likely to result in lower efficiency than an asynchronous strategy. The exercise testing scenario may help dictate which method is ultimately chosen.     

Effects of playing surface on physiological responses and performance variables in a controlled football simulation

Abstract

In spite of the increased acceptance of artificial turf in football, few studies have investigated if matches are altered by the type of surface used and no research has compared physiological responses to football activity on artificial and natural surfaces. In the present study, participants performed a football match simulation on high-quality artificial and natural surfaces. Neither mean heart rate (171 ± 9 beats · min^?1 vs. 171 ± 9 beats · min^?1; P > 0.05) nor blood lactate (4.8 ± 1.6 mM vs. 5.3 ± 1.8 mM; P > 0.05) differed between the artificial and natural surface, respectively. Measures of sprint, jumping and agility performance declined through the match simulation but surface type did not affect the decrease in performance. For example, the fatigue index of repeated sprints did not differ (P > 0.05) between the artificial, (6.9 ± 2.1%) and natural surface (7.4 ± 2.4%). The ability to turn after sprinting was affected by surface type but this difference was dependent on the type of turn. Although there were small differences in the ability to perform certain movements between artificial and natural surfaces, the results suggest that fatigue and physiological responses to football activity do not differ markedly between surface-type using the high-quality pitches of the present study.     

不同压力下肢紧身服对跑步运动中摄氧量及运动后血乳酸恢复的影响

研究目的:研究穿着不同压力下肢紧身服对跑步过程中摄氧量以及运动后血乳酸恢复的影响。研究方法:选择北京体育大学12名健康男性长跑爱好者作为研究对象。受试者进行3次递增负荷最大摄氧量测试,在测试期间随机穿戴不同压力的下肢紧身服和普通运动长裤进行测试。最大摄氧量测试采用METAMAX 3B心肺功能测试系统进行测试,根据Bruce测试方案每3 min递增负荷,直至受试者运动至力竭。分别在安静时、运动后1 min、4 min、7 min和10 min 5个时刻测量血乳酸指标。采用Simi Aktisys 3D实验设备进行肌肉震动测试。采用一般线性模型的重复测量统计学方法比较3种情况下各项指标的差异。研究结果:运动过程中,高压力下肢紧身服在第二负荷上的耗氧量显著减小(P=0.047),但在其他负荷的耗氧量以及最大摄氧量没有出现显著性的差异。不同压力下肢紧身服对乳酸最大值以及乳酸消除速率没有产生显著性的影响。不同压力下肢紧身服均能够显著减小股四头肌、股二头肌和腓肠肌的肌肉震动(P=0.017、P=0.012、P=0.028),并且压力较大的下肢紧身服对肌肉的固定效果更好。研究结论:不同压力下肢紧身服对一次性高强度跑步运动过程中的最大摄氧量没有显著性的影响,但有可能在一定运动强度范围内减少运动过程中氧气的消耗。下肢紧身服对一次性高强度跑步运动后乳酸恢复没有显著性的影响。下肢紧身服能够降低肌肉的额外震动,并且压力越大,效果越好。     

The effect of crank rate strategy on peak aerobic power and peak physiological responses during arm crank ergometry

Abstract

The main aim of this study was to determine whether the use of an imposed or freely chosen crank rate would influence submaximal and peak physiological responses during arm crank ergometry. Fifteen physically active men participated in the study. Their mean age, height, and body mass were 25.9 (s = 6.2) years, 1.80 (s = 0.10) m, and 78.4 (s = 6.1) kg, respectively. The participants performed two incremental peak oxygen consumption ([Vdot]O_2peak) tests using an electronically braked ergometer. One test was performed using an imposed crank rate of 80 rev · min^?1, whereas in the other the participants used spontaneously chosen crank rates. The order in which the tests were performed was randomized, and they were separated by at least 2 days. Respiratory data were collected using an on-line gas analysis system, and fingertip capillary blood samples (～20 μl) were collected for the determination of blood lactate concentration. Heart rate was also recorded throughout the tests. Time to exhaustion was measured and peak aerobic power calculated. Submaximal data were analysed using separate two-way repeated-measures analyses of variance, while differences in peak values were analysed using separate paired t-tests. Variations in spontaneously chosen crank rate were assessed using a one-way analysis of variance with repeated measures. Agreement between the crank rate strategies for the assessment of peak values was examined by calculating intra-class correlation coefficients (ICC) and 95% limits of agreement (95% LoA). While considerable between-participant variations in spontaneously chosen crank rate were observed, the mean value was not different (P > 0.05) from the imposed crank rate of 80 rev · min^?1 at any point. No differences (P > 0.05) were observed for submaximal data between crank strategies. Furthermore, mean peak minute power [158 (s = 20) vs. 158 (s = 18) W], time to exhaustion [739 (s = 118) vs. 727 (s = 111) s], and [Vdot]O_2peak[3.09 (s = 0.38) vs. 3.04 (s = 0.34) l · min^?1] were similar for the imposed and spontaneously chosen crank rates, respectively. However, the agreement for the assessment of [Vdot]O_2peak (ICC = 0.78; 95% LoA = 0.04 ± 0.50 l · min^?1) between the cranking strategies was considered unacceptable. Our results suggest that either an imposed or spontaneously chosen crank rate strategy can be used to examine physiological responses during arm crank ergometry, although it is recommended that the two crank strategies should not be used interchangeably.     

Effects of intense exercise on the physiological and mental condition of female university judoists during a training camp

Abstract

To clarify the physical and mental fatigue caused by intense exercise and the relationship between the two types of fatigue, we examined changes in anthropometric and biochemical variables, neutrophil function, and the Profile of Mood States (POMS) questionnaire in 13 female university judoists attending a one-week training camp. Blood glucose, total cholesterol, haemoglobin, leukocyte count, IgG, and phagocytic activity all decreased after the training camp compared with baseline (P ≤ 0.046). Aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and neutrophil oxidative burst activity increased after the training camp (P ≤ 0.007). Of the POMS scores, that for Fatigue increased after the training camp (P = 0.041) and that for Vigour decreased (P = 0.042). The changes in several POMS scores correlated with the changes in blood biochemical variables. In particular, the change in Total mood disturbance was negatively associated with changes in myogenic enzymes (P ≤ 0.032). Our results suggest that intense exercise during training camps for female judoists leads to the appearance and accumulation of mental and physical fatigue, which are related to each other.