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

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; VO(2max) 55.5 ml x kg(-1) x min(-1), s = 5.8) undertook repeated sprints at 120% of the speed at which VO(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.     

Perceptual and cognitive responses during exercise: Relationships with metamotivational state and dominance

Abstract

In this study, we examined ratings of perceived exertion (RPE) and attentional focus during exercise in relation to telic and paratelic metamotivational dominance and state. Thirty regular exercisers (11 females, 19 males), of whom 10 were telic dominant (mean Paratelic Dominance Scale score=6.2±2.9), 10 paratelic dominant (mean PDS score=23.8±1.4), and 10 non-dominant (mean PDS score=15.4±0.7) completed two exercise trials. In the first trial, the participants completed a maximal ramped exercise test on a motorized treadmill to determine their gas exchange threshold (the speed at which determined exercise intensity of the subsequent trial). Throughout the second trial (a 30-min treadmill run), the participants reported their metamotivational state, RPE, and attentional focus (associative or dissociative) at 5-min intervals. Heart rate was recorded at 3, 8, 13, 18, 23, and 28 min and expired air was analysed for oxygen consumption (VO₂) between 1–3, 6–8, 11–13, 16–18, 21–23, and 26–28 min. There was no main effect of dominance or dominance×time interaction on any variables (P >0.05). Oxygen consumption did not differ between states but RPE was higher in the telic than paratelic state at 25 and 30 min (t ₂₈=2.87, P <0.05; t _26.77=3.88, P <0.05, respectively). Attentional focus was more associative in the telic than paratelic state at 20, 25, and 30 min (t ₂₈=? 3.73, P <0.05; t ₂₈=? 4.85, P <0.01; t ₂₈=? 5.15, P <0.05, respectively) and heart rate was higher at 23 min in the telic state (t ₂₇=3.40, P <0.05). During the latter stages of exercise, the telic metamotivational state, not dominance, was related to a more associative attentional focus and higher RPE. Our results support the use of reversal theory (Apter, 2001) to understand perceptual and cognitive responses during aerobic exercise, but an experimental design in which state is manipulated is needed to examine the effects of metamotivational dominance and state on perceptual and cognitive responses.     

Caffeine lowers perceptual response and increases power output during high-intensity cycling

The aim of this study was to determine the effects of caffeine ingestion on a ‘preloaded’ protocol that involved cycling for 2?min at a constant rate of 100% maximal power output immediately followed by a 1-min ‘all-out’ effort. Eleven male cyclists completed a ramp test to measure maximal power output. On two other occasions, the participants ingested caffeine (5?mg?·?kg^?1) or placebo in a randomized, double-blind procedure. All tests were conducted on the participants' own bicycles using a Kingcycle? test rig. Ratings of perceived exertion (RPE; 6–20 Borg scale) were lower in the caffeine trial by approximately 1 RPE point at 30, 60 and 120?s during the constant rate phase of the preloaded test (P?<0.05). The mean power output during the all-out effort was increased following caffeine ingestion compared with placebo (794±164 vs 750±163?W; P?=?0.05). Blood lactate concentration 4, 5 and 6?min after exercise was also significantly higher by approximately 1?mmol?·?l^?1 in the caffeine trial (P?<0.05). These results suggest that high-intensity cycling performance can be increased following moderate caffeine ingestion and that this improvement may be related to a reduction in RPE and an elevation in blood lactate concentration.     

血液氧自由基、血乳酸、主观用力感觉、心率与运动强度相关性的研究

为探索抗氧化运动强度与监控指标的确定,采用CR2000RC氧自由基生化分析仪、LT 1710血乳酸测定仪、Borg(15、10)主观用力感觉等级量表、心率监测系统对受试者(n=9)从事300、600、900、1200、1500KPM/min不同强度踏车(Monark839E)运动(每级负荷运动5min)时血液氧自由基、血乳酸、主观用力感觉、心率的变化进行测定,并对其进行了相关性分析。结果表明:心率、RPE(15、10)与运动强度(KPM/min)之间呈现高度线性相关,r=0 959、0 923、0 918;血液氧自由基浓度与运动强度、心率、RPE之间的相关性较低,但其变化趋势类似于血乳酸的变化,低强度时(≤900KPM/min)虽运动强度增加但血液氧自由基浓度保持不变,当运动强度超过900KPM/min时,血液氧自由基浓度随运动强度增加而增加;RPE10与血乳酸之间的相关程度高于RPE15、心率、运动强度与血乳酸的相关程度。认为心率、RPE(15、10)可作为监控抗氧化运动强度的理想指标;血液氧自由基浓度不能作为运动强度的监控指标;从抗氧化运动角度而言,健身运动的强度应以血乳酸4mM、心率130beats/min、RPE15值11、RPE10值3左右为宜。     

Effects of compression garments on surface EMG and physiological responses during and after distance running

BackgroundThe few previous studies that focused on the effects of compression garments (CG) on distance running performance have simultaneously measured electromyogram, physiological, and perceptual parameters. Therefore, this study investigated the effects of CG on muscle activation and median frequency during and after distance running, as well as blood-lactate concentration and rating of perceived exertion (RPE) during distance running.MethodsEight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials, one with CG, and the other with control garment made of normal cloth. The RPE and the surface electromyography (EMG) of 5 lower extremity muscles including gluteus maximus (GM), rectus femoris (RF), semitendinosus (ST), tibialis anterior (TA), and gastrocnemius (GAS) were measured during the running trial. The blood-lactate levels before and after the running trial were measured.ResultsWearing CG led to significant lower muscle activation (p < 0.05) in the GM (decreased 7.40%–14.31%), RF (decreased 4.39%–4.76%), and ST (decreased 3.42%–7.20%) muscles; moreover, significant higher median frequency (p < 0.05) in the GM (increased 5.57%) and ST (increased 10.58%) muscles. Wearing CG did not alter the RPE values or the blood-lactate levels (p > 0.05).ConclusionWearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running. This finding suggested that wearing CG may improve muscle function, which might enhance running performance and prevent muscle fatigue.     

Effects of a carbohydrate and caffeine gel on intermittent sprint performance in recreationally trained males

Abstract

We investigated the effects of ingesting carbohydrate gels with and without caffeine on a ~90-minute, four blocks intermittent sprint test (IST), in 12 recreationally trained male athletes. Using a cross-over design, one 70 ml dose of gel containing either 25 g of carbohydrate with (CHOCAF) or without (CHO) 100 mg of caffeine, or a non-caloric placebo (PL) was ingested on three occasions: one hour before, immediately prior to and during the IST. Blood glucose, rating of perceived exertion (RPE) and fatigue index (FI) were analysed. Glucose showed significantly higher values for both CHOCAF and CHO at the first (p=0.005 and p=0.000, respectively), second (p=0.009 and 0.008, respectively) and third (p=0.003 and 0.001, respectively) blocks when compared with PL, while only CHOCAF was significantly different to PL (p=0.002) at the fourth block. CHOCAF showed an improved FI (mean 5.0, s =1.7) compared with CHO (mean 7.6, s =2.6; p=0.006) and PL (mean 7.4, s =2.4; p=0.005), a significantly lower RPE (mean 14.2, s =2) compared with PL (mean 15.3, s =2; p=0.003) and a trend in respect of CHO (mean 14.9, s =2.3; p=0.056) after the third block. In conclusion, ingesting CHOCAF one hour before, prior to and during an IST is effective at transiently reducing fatigue and RPE whilst maintaining higher glucose levels at the final stages of the exercise.     

Exercise-induced hypoalgesia: Pain tolerance,preference and tolerance for exercise intensity,and physiological correlates following dynamic circuit resistance exercise

Previous research has demonstrated significant decreases in pain perception in healthy individuals following both aerobic and upper body resistance exercise, but research on circuit training has been limited. The purpose of the study was to determine the effects of a strenuous bout of dynamic circuit resistance exercise on pain threshold and pain tolerance in conjunction with changes in blood lactate levels, heart rate (HR), and perceived exertion. A sample of 24 college-age students participated in 2 sessions: (1) a maximal strength testing session and (2) a circuit training bout of exercise that consisted of 3 sets of 12 repetitions with a 1:1 work to rest ratio at 60% one-repetition maximum (1-RM) predicted from a three-repetition maximum (3-RM) for 9 exercises. Participants exhibited increases in pain tolerance, blood lactate levels, HR and perceived exertion following resistance exercise. Preference for exercise intensity was positively correlated with lactate post exercise and tolerance for exercise intensity was positively correlated with pain tolerance and lactate post exercise. In conclusion, this is the first study to demonstrate increases in pain tolerance following a dynamic circuit resistance exercise protocol and disposition for exercise intensity may influence lactate and pain responses to circuit resistance exercise.     

The effects of combined glucose-electrolyte and sodium bicarbonate ingestion on prolonged intermittent exercise performance

Abstract

This study examined the effects of combined glucose and sodium bicarbonate ingestion prior to intermittent exercise. Ninemales (mean ± s age 25.4 ± 6.6 years, body mass 78.8 ± 12.0 kg, maximal oxygen uptake ([Vdot]O_2max) 47.0 ± 7ml · kg · min^?1) undertook 4 × 45 min intermittent cycling trials including 15 × 10 s sprints one hour after ingesting placebo (PLA), glucose (CHO), sodium bicarbonate (NaHCO₃) or a combined CHO and NaHCO₃ solution (COMB). Post ingestion blood pH (7.45 ± 0.03, 7.46 ± 0.03, 7.32 ± 0.05, 7.32 ± 0.01) and bicarbonate (30.3 ± 2.1, 30.7 ± 1.8, 24.2 ± 1.2, 24.0 ± 1.8 mmol · l^?1) were greater for NaHCO₃ and COMB when compared to PLA and CHO, remaining elevated throughout exercise (main effect for trial; P < 0.05). Blood lactate concentration was greatest throughout exercise for NaHCO₃ and COMB (main effect for trial; P < 0.05). Blood glucose concentration was greatest 15 min post-ingestion for CHO followed by COMB, NaHCO₃ and PLA (7.13 ± 0.60, 5.58 ± 0.75, 4.51 ± 0.56, 4.46 ± 0.59 mmol · l^?1, respectively; P < 0.05). Gastrointestinal distress was lower during COMB compared to NaHCO₃ at 15 min post-ingestion (P < 0.05). No differences were observed for sprint performance between trials (P = 1.00). The results of this study suggest that a combined CHO and NaHCO₃ beverage reduced gastrointestinal distress and CHO availability but did not improve performance. Although there was no effect on performance an investigation of the effects in more highly trained individuals may be warranted.     

The effects of stretching on knee flexor fatigue and perceived exertion

Abstract

The objective of this study was to examine the effects of acute static muscle stretch on hamstring muscle fatigue and perceived exertion between young adult men and women. Twenty volunteers participated in two experimental sessions, in which we assessed maximal-effort isokinetic knee flexor force (90° · s^?1) and the number of sub-maximal (50% maximal) knee flexor repetitions to the point of failure. Immediately before the sub-maximal contractions on one randomly selected session, participants received ten 30-s passive knee flexor muscle stretches. Perceived exertion was sampled with a modified Borg category-ratio scale following each sub-maximal repetition. Each participant's perceived exertion response was estimated every 10% across the sub-maximal repetitions, via linear interpolation and power-function modelling. The men generated significantly greater force than the women during both experimental sessions, while muscle stretching had no significant effect on the number of sub-maximal repetitions. When estimated via power-function modelling, perceived exertion increased at a significantly greater rate following muscle stretch. Perceived exertion was significantly greater for the women following muscle stretch than the men. The findings suggest that the elevation in perceived exertion following knee flexor muscle stretching may be greater in women than men, despite no significant alterations in mechanical measures of muscle fatigue.     

A novel method for the performance of isometric exercise in the home

There is a paucity of research on devices suitable for home-based isometric exercise. Our aim was to compare cardiovascular responses to isometric exercise using novel and established methods. Ten individuals (age 34.0?±?8.5 years, mass 68.2?±?10.4?kg, height 1.72?±?0.09?m; mean?±?s) performed three different isometric exercise protocols with 48?h between each. Each protocol involved four repeated exercise bouts of 2?min at 30% maximum voluntary contraction force using alternate legs (transducer), alternate arms (transducer), or alternate arms (novel device). Systolic blood pressure, diastolic blood pressure, mean arterial blood pressure and heart rate were measured every 30?s. The highest (peak) values during each 2?min bout of exercise were recorded (peak systolic blood pressure, peak diastolic blood pressure, peak mean arterial blood pressure and peak heart rate). At the end of each 2?min exercise bout, the participants rated their perceived discomfort using Borg's CR-10 scale. There was a statistically significant difference in peak systolic blood pressure between isometric arm flexion using the force transducer and the novel device [158.1?±?10.8 vs. 149.1?±?13.9?mmHg (mean?±?s); P = 0.02]. Further analysis showed that peak systolic blood pressure was on average 9?mmHg higher using the force transducer with limits of agreement of –?15.97 to 33.97?mmHg. Analysis of the peak diastolic blood pressure, peak mean arterial blood pressure, peak heart rate and CR-10 data revealed no statistically significant differences between the three protocols. These results suggest that this novel, home-based method elicited similar cardiovascular responses during isometric exercise to those of established laboratory-based methods. However, the lower peak systolic blood pressure using the modified scales warrants further investigation before this method is used widely in the home.     

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 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.     

The effects of work-rest duration on intermittent exercise and subsequent performance

This study examined the effects of different work - rest durations during 40 min intermittent treadmill exercise and subsequent running performance. Eight males (mean +/- s: age 24.3 +/- 2.0 years, body mass 79.4 +/- 7.0 kg, height 1.77 +/- 0.05 m) undertook intermittent exercise involving repeated sprints at 120% of the speed at which maximal oxygen uptake (nu-VO2max) was attained with passive recovery between each one. The work - rest ratio was constant at 1:1.5 with trials involving short (6:9 s), medium (12:18 s) or long (24:36 s) work - rest durations. Each trial was followed by a performance run to volitional exhaustion at 150% nu-VO2max. After 40 min, mean exercise intensity was greater during the long (68.4 +/- 9.3%) than the short work - rest trial (54.9 +/- 8.1% VO2max; P < 0.05). Blood lactate concentration at 10 min was higher in the long and medium than in the short work - rest trial (6.1 +/- 0.8, 5.2 +/- 0.9, 4.5 +/- 1.3 mmol x l(-1), respectively; P < 0.05). The respiratory exchange ratio was consistently higher during the long than during the medium and short work - rest trials (P < 0.05). Plasma glucose concentration was higher in the long and medium than in the short work - rest trial after 40 min of exercise (5.6 +/- 0.1, 6.6 +/- 0.2 and 5.3 +/- 0.5 mmol x l(-1), respectively; P < 0.05). No differences were observed between trials for performance time (72.7 +/- 14.9, 63.2 +/- 13.2, 57.6 +/- 13.5 s for the short, medium and long work - rest trial, respectively; P = 0.17), although a relationship between performance time and 40 min plasma glucose was observed (P < 0.05). The results show that 40 min of intermittent exercise involving long and medium work - rest durations elicits greater physiological strain and carbohydrate utilization than the same amount of intermittent exercise undertaken with a short work-rest duration.     

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.     

Effect of creatine plus caffeine supplements on time to exhaustion during an incremental maximum exercise

Abstract

This study investigated the effects of acute caffeine ingestion following short-term creatine supplementation on an incremental cycling to exhaustion task. Twelve active males performed the task under three conditions: baseline condition (BASE, no ergogenic aid), creatine plus caffeine condition (CRE + CAF), and creatine with placebo condition (CRE + PLA). Following the establishment of BASE condition, participants were administered CRE + CAF (0.3 g·kg^?1·day^?1 of creatine for 5 days followed by 6 mg·kg^?1 of caffeine 1 h prior to testing) and CRE + PLA (0.3 g·kg^?1·day^?1 of creatine for 5 days followed by 6 mg·kg^?1 of placebo 1 h prior to testing) in a double-blind, randomized crossover and counterbalancing protocol. No significant differences were observed in relative maximal oxygen consumption ([Vdot]O_2max) (51.7±5.5, 52.8±4.9 and 51.3±5.6 ml·kg^?1·min^?1 for BASE, CRE + CAF and CRE + PLA, respectively; P>0.05) and absolute [Vdot]O_2max (3.6±0.4, 3.7±0.4 and 3.5±0.5 l·min^?1 for BASE, CRE + CAF and CRE + PLA, respectively; P>0.05). Blood samples indicated significantly higher blood lactate and glucose concentrations in the CRE + CAF among those in the BASE or CRE + PLA condition during the test (P<0.05). The time to exhaustion on a cycling ergometer was significantly longer for CRE + CAF (1087.2±123.9 s) compared with BASE (1009.2±86.0 s) or CRE + PLA (1040.3±96.1 s). This study indicated that a single dose of caffeine following short-term creatine supplementation did not hinder the creatine–caffeine interaction. In fact, it lengthened the time to exhaustion during an incremental maximum exercise test. However, this regime might lead to the accumulation of lactate in the blood.     

Comparison of treadmill and over-ground Nordic walking

Abstract

The purpose of this study was to compare the physiological responses of Nordic walking on a specially designed treadmill and Nordic walking on a level over-ground surface. Thirteen participants completed three 1-h Nordic walking training sessions. Following the training sessions, each participant performed two 1600-m over-ground Nordic walking trials at a self-selected pace. Each participant then completed two 1600-m Nordic walking treadmill trials on a Hammer Nordic Walking XTR Treadmill®, at the mean walking speed of their two over-ground Nordic walking trials. Breath-by-breath analysis of oxygen uptake ([Vdot]O₂) and heart rate was performed during each trial. Caloric expenditure was calculated using the [Vdot]O₂. Rating of perceived exertion (RPE) was assessed at the end of each trial. We found no significant differences in physiological variables collected during the two over-ground Nordic walking trials or the two treadmill Nordic walking trials. Mean walking speed was 106.96±11.49 m · min^?1. Mean heart rate during treadmill walking (99±13 beats · min^?1) was 22% lower than that during the over-ground condition (126±17 beats · min^?1). Mean [Vdot]O₂ and mean caloric expenditure were also lower during treadmill walking (15.18±3.81 ml · min^?1 · kg^?1, 0.08±0.02 kcal · min^?1 · kg^?1) than over-ground walking (24.16±4.89 ml · min^?1 · kg^?1, 0.12±0.02 kcal · min^?1 · kg^?1). Analysis of variance demonstrated that all variables were significantly higher during over-ground Nordic walking (P<0.001). A Mann-Whitney U-test demonstrated that the RPE for over-ground Nordic walking was greater than that for treadmill Nordic walking (P=0.02). Thus over-ground Nordic walking created a greater physiological stress than treadmill Nordic walking performed at the same speed and distance. The reason for this difference may have been the relatively narrow walking and poling decks on the treadmill, which made it difficult for the participants to place their poles correctly and maintain a consistent walking pattern. This would decrease the contribution of the arm muscles to overall oxygen consumption. In conclusion, the Hammer Nordic Walking XTR Treadmill® does not replicate the physiological stress of over-ground Nordic walking. Increasing the width of the decks could eliminate the discrepancy.     

Sodium bicarbonate ingestion and its effects on anaerobic exercise of various durations

Abstract

Four groups of male subjects participated in anaerobic testing on a Repco EX 10 cycle ergometer to determine the effectiveness of sodium bicarbonate (0.3 g kg^‐1 body mass) as an ergogenic aid during exercise of 10, 30, 120 and 240 s duration. Blood was collected 90 min prior to ingestion of sodium bicarbonate (NaHCO₃), after ingestion of NaHCO₃ and immediately post‐exercise from a heated (43–46°C) fingertip and analysed immediately post‐collection for pH, base excess, bicarbonate and lactate. The total work undertaken (kj) and peak power achieved during the tests were also obtained via a Repco Work Monitor Unit. Blood bicarbonate levels were again increased above the control and placebo conditions (P< 0.001) and blood lactate levels were also increased following the bicarbonate trials. The pH levels fell significantly (P<0.05) below the control and placebo conditions in all trials. The results indicate that NaHCO₃ at this dosage has no ergogenic benefit for work of either 10 or 30 s duration, even though blood bicarbonate levels were significantly increased (P<0.05) following ingestion of NaHCO₃. For work periods of 120 and 240 s, performance was significantly increased (P<0.05) above the control and placebo conditions following NaHCO₃ ingestion.     

Systematic review of the acute and chronic effects of high-intensity interval training on executive function across the lifespan

ABSTRACT

Research regarding the effects of high-intensity interval training (HIIT) on executive function has grown exponentially in recent years. However, there has been no comprehensive review of the current state of literature. Therefore, the aim of this systematic review is to summarize previous research regarding the acute and chronic effects of HIIT on executive function across the lifespan and highlight future research directions. The results indicated that acute bouts of HIIT has a positive effect on inhibition in children/adolescents and adults, and further that chronic HIIT benefits inhibition and working memory in children. More research employing chronic interventions, focusing on middle-aged and older adults, and examining the effects on the working memory and cognitive flexibility domains of executive function are needed. Future research should also focus on a) the use of stronger research designs, b) the effects of HIIT dosage/modality, c) consideration of individual differences, d) possible underlying mechanisms, and e) examining the feasibility of translating HIIT to real-word settings.