Kevin De Pauw

Guidelines to Classify Subject Groups in Sport-Science Research

AIM To review current cycling-related sport-science literature to formulate guidelines to classify female subject groups and to compare this classification system for female subject groups with the classification system for male subject groups. METHODS A database of 82 papers that described female subject groups containing information on preexperimental maximal cycle-protocol designs, terminology, biometrical and physiological parameters, and cycling experience was analyzed. Subject groups were divided into performance levels (PLs), according to the nomenclature. Body mass, body-mass index, maximal oxygen consumption (VO2max), peak power output (PPO), and training status were compared between PLs and between female and male PLs. RESULTS Five female PLs were defined, representing untrained, active, trained, well-trained, and professional female subjects. VO2max and PPO significantly increased with PL, except for PL3 and PL4 (P < .01). For each PL, significant differences were observed in absolute and relative VO2max and PPO between male and female subject groups. Relative VO2max is the most cited parameter for female subject groups and is proposed as the principal parameter to classify the groups. CONCLUSION This systematic review shows the large variety in the description of female subject groups in the existing literature. The authors propose a standardized preexperimental testing protocol and guidelines to classify female subject groups into 5 PLs based on relative VO2max, relative PPO, training status, absolute VO2max, and absolute PPO.

Does a period of detraining cause a decrease in serum brain-derived neurotrophic factor?

Brain-derived neurotrophic factor (BDNF) is one of the neurotrophins promoting cognitive function and contributing to neurogenesis and neuroprotection. Available evidence suggests that exercise influences serum BDNF concentrations, but that the effect is transient. The purpose of this study is to determine whether a period of aerobic training, followed by a period of detraining, can influence basal serum BDNF levels in humans. Sixteen young, sedentary subjects were assigned to an experimental group (n=9) and a control group (n=7). The experimental group performed an aerobic training program during 8 weeks, followed by 8 weeks of detraining, during which subjects returned to their previous, sedentary activity level. The control group remained physically inactive during 16 weeks. In both groups, performance on short-term (Digit Span test) and mid-term memory (Recall of Images) was assessed. Aerobic training significantly increased the VO(2) peak in the experimental group, and these values returned to baseline after 8 weeks of detraining. Basal serum BDNF was not influenced by 8 weeks of aerobic training and detraining did not seem to have an effect on basal peripheral BDNF concentrations. Both training and detraining did not clearly influence short-term memory performance on the Digit Span test and no differences were present between the experimental and control group on the mid-term memory test. Future studies should focus on patient groups and elderly to further investigate the effect of training and detraining on neurotrophic factors and cognitive function, and on the effects of training and detraining on the BDNF response to acute exercise.

Brain mapping after prolonged cycling and during recovery in the heat

The aim of this study was to determine the effect of prolonged intensive cycling and postexercise recovery in the heat on brain sources of altered brain oscillations. After a max test and familiarization trial, nine trained male subjects (23 ± 3 yr; maximal oxygen uptake = 62.1 ± 5.3 ml·min(-1)·kg(-1)) performed three experimental trials in the heat (30°C; relative humidity 43.7 ± 5.6%). Each trial consisted of two exercise tasks separated by 1 h. The first was a 60-min constant-load trial, followed by a 30-min simulated time trial (TT1). The second comprised a 12-min simulated time trial (TT2). After TT1, active recovery (AR), passive rest (PR), or cold water immersion (CWI) was applied for 15 min. Electroencephalography was measured at baseline and during postexercise recovery. Standardized low-resolution brain electromagnetic tomography was applied to accurately pinpoint and localize altered electrical neuronal activity. After CWI, PR and AR subjects completed TT2 in 761 ± 42, 791 ± 76, and 794 ± 62 s, respectively. A prolonged intensive cycling performance in the heat decreased β activity across the whole brain. Postexercise AR and PR elicited no significant electrocortical differences, whereas CWI induced significantly increased β3 activity in Brodmann areas (BA) 13 (posterior margin of insular cortex) and BA 40 (supramarginal gyrus). Self-paced prolonged exercise in the heat seems to decrease β activity, hence representing decreased arousal. Postexercise CWI increased β3 activity at BA 13 and 40, brain areas involved in somatosensory information processing.

Effect of Five Different Recovery Methods on Repeated Cycle Performance

PURPOSE The aim of this study was to determine the influence of five different recovery strategies on repeated simulated time trial (TT) performance on a stationary cycle ergometer. METHODS Study 1 (n=8, male, club-level trained; V˙O2max: 56.9 ± 3.8 mL·min·kg) investigated the influence of passive rest with or without upper leg cooling (cooling device set at 0 °C or 10 °C) and compression after a first time trial (TT1) on a second time trial (TT2). Study 2 (n=9, male, club-level trained; V˙O2max: 53.3 ± 5.2 mL·min·kg) examined the influence of active recovery (AR) with or without upper leg cooling (cooling device set at 0 °C) applied after TT1 on TT2. Exhaustive exercise consisted of a cycle exercise at 55% Wmax lasting 30 min, immediately followed by a TT in which subjects had to complete a preset amount of work, equal to 30 min at 75% Wmax, as fast as possible. Immediately after TT1, a different recovery intervention was used for 20 min, and then subjects passively rested for 100 min before starting TT2. TT performance and physiological parameters were registered during the experiments. RESULTS In both studies, we observed that TT performance did not significantly change for either of the recovery interventions. During the cooling interventions, skin temperatures significantly decreased (P<0.05). AR + cooling + compression versus AR (study 2) clearly showed a significantly (P<0.05) faster decrease of the blood lactate concentration ([BLa]) during the recovery period after TT1 and a lower [BLa] during TT2. CONCLUSIONS Twenty minutes after cooling (device set at 0 °C or 10 °C), AR or the combined recovery method had comparable effects as passive recovery on the maintenance of TT2 performance 120 min after the first TT (TT1). After AR, however, subjects seemed to perform slightly better during TT2.

Cycling on a Bike Desk Positively Influences Cognitive Performance

Purpose Cycling desks as a means to reduce sedentary time in the office has gained interest as excessive sitting has been associated with several health risks. However, the question rises if people will still be as efficient in performing their desk-based office work when combining this with stationary cycling. Therefore, the effect of cycling at 30% Wmax on typing, cognitive performance and brain activity was investigated. Methods After two familiarisation sessions, 23 participants performed a test battery [typing test, Rey auditory verbal learning test (RAVLT), Stroop test and Rosvold continuous performance test (RCPT)] with electroencephalography recording while cycling and sitting on a conventional chair. Results Typing performance, performance on the RAVLT and accuracy on the Stroop test and the RCPT did not differ between conditions. Reaction times on the Stroop test and the RCPT were shorter while cycling relative to sitting (p < 0.05). N200, P300, N450 and conflict SP latency and amplitude on the Stroop test and N200 and P300 on the RCPT did not differ between conditions. Conclusions This study showed that typing performance and short-term memory are not deteriorated when people cycle at 30% Wmax. Furthermore, cycling had a positive effect on response speed across tasks requiring variable amounts of attention and inhibition.

Effect of recovery interventions on cycling performance and pacing strategy in the heat.

PURPOSE To determine the effect of active recovery (AR), passive rest (PR), and cold-water immersion (CWI) after 90 min of intensive cycling on a subsequent 12-min time trial (TT2) and the applied pacing strategy in TT2. METHODS After a maximal test and familiarization trial, 9 trained male subjects (age 22 ± 3 y, VO2max 62.1 ± 5.3 mL · min-1 · kg-1) performed 3 experimental trials in the heat (30°C). Each trial consisted of 2 exercise tasks separated by 1 h. The first was a 60-min constant-load trial at 55% of the maximal power output followed by a 30-min time trial (TT1). The second comprised a 12-min simulated time trial (TT2). After TT1, AR, PR, or CWI was applied for 15 min. RESULTS No significant TT2 performance differences were observed, but a 1-sample t test (within each condition) revealed different pacing strategies during TT2. CWI resulted in an even pacing strategy, while AR and PR resulted in a gradual decline of power output after the onset of TT2 (P ≤ .046). During recovery, AR and CWI showed a trend toward faster blood lactate ([BLa]) removal, but during TT2 significantly higher [BLa] was only observed after CWI compared with PR (P = .011). CONCLUSION The pacing strategy during subsequent cycling performance in the heat is influenced by the application of different postexercise recovery interventions. Although power was not significantly altered between groups, CWI enabled a differently shaped power profile, likely due to decreased thermal strain.

Effects of mental fatigue on endurance performance in the heat

Purpose Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity and has been observed to decrease time trial (TT) endurance performance by ∼3.5% in normal ambient temperatures. Recently, it has been suggested that heat may augment the negative effect of mental fatigue on cognitive performance, raising the question whether it may also amplify the effect of mental fatigue on TT performance. Methods In 30°C and 30% relative humidity, 10 endurance-trained male athletes (mean ± SD; age = 22 ± 3 yr, Wmax = 332 ± 41 W) completed two experimental conditions: intervention (I; 45-min Stroop task) and control (C; 45-min documentary). Pre- and postintervention/control, cognitive performance was followed up with a 5-min Flanker task. Thereafter, subjects cycled for 45 min at a fixed pace equal to 60% Wmax, immediately followed by a self-paced TT in which they had to produce a fixed amount of work (equal to cycling 15 min at 80% Wmax) as fast as possible. Results Self-reported mental fatigue was significantly higher after I compared with C (P < 0.05). Moreover EEG measures also indicated the occurrence of mental fatigue during the Stroop (P < 0.05). TT did not differ between conditions (I = 906 ± 30 s, C = 916 ± 29 s). Throughout exercise, physiological (HR, blood lactate, core, and skin temperature) and perceptual measures (perception of effort and thermal sensation) were not affected by mental fatigue. Conclusion No negative effects of mild mental fatigue were observed on performance and the physiological and perceptual responses to endurance exercise in the heat. Most plausibly, mild mental fatigue does not reduce endurance performance when the brain is already stressed by a hot environment.

Bike Desks in the Office: Physical Health, Cognitive Function, Work Engagement, and Work Performance

Objective: The aim of this study was to examine the longitudinal effect of implementing bike desks in an office setting on physical health, cognition, and work parameters. Methods: Physical health, cognitive function, work engagement, and work performance measured before (T0) and after (T2) the intervention period were compared between office workers who used the bike desk (IG, n = 22) and those who did not (CG, n = 16). Results: The IG cycled approximately 98 minutes/week. The IG showed a significantly lower fat percentage and a trend toward a higher work engagement at T2 relative to T0, while this was not different for the CG. No effects on other parameters of health, cognition, or work performance were found. Conclusions: Providing bike desks in the office positively influences employees’ fat percentage and could positively influence work engagement without compromising work performance.

Do Glucose and Caffeine Nasal Sprays Influence Exercise or Cognitive Performance

INTRODUCTION Nasal spray (NAS) containing caffeine (CAF) or glucose (GLUC) activates sensory(motor) cortices. PURPOSE To investigate the influence of CAF or GLUC NAS on exercise and cognitive performance. METHODS Eleven male subjects (age 22 ± 2 y) performed a maximal cycle test and 2 familiarization and 3 experimental trials. Each trial included a 30-s Wingate test and a 30-min time-trial (TT) performance test interspersed by 15 min of rest. Before and after each exercise test a Stroop task was conducted. Placebo NAS with or without CAF or GLUC was provided before each exercise session and at each completed 25% of the TT. Exercise-performance, physiological, and cognitive measures were obtained. Magnitude-based inferences determined the likelihood that NAS solutions would be beneficial, trivial, or negative to exercise-performance measures based on the smallest worthwhile effect. Physiological and cognitive measures were analyzed using (non)parametric tests (P < .05). RESULTS GLUC NAS substantially increased the average power output during the TT (very likely beneficial: 98%). No further worthwhile exercise-performance enhancements were found for both substances. In addition, no significant differences in physiological and cognitive measures were observed. In line with mouth rinsing, GLUC was shown to substantially enhance endurance performance, probably due to the activation of the olfactory pathway and/or extra-oral sweet-taste receptors. CONCLUSION GLUC NAS enhances endurance performance, which indicates a novel administration route. The higher activity in sensory brain cortices probably elicited the ergogenic effect. However, no further physiological and cognitive changes occurred, indicating that higher doses of substrates might be required.

The efficacy of the Ankle Mimicking Prosthetic Foot prototype 4.0 during walking: Physiological determinants

Background: Evaluating the effectiveness of a novel prosthetic device during walking is an important step in product development. Objective: To investigate the efficacy of a novel quasi-passive ankle prosthetic device, Ankle Mimicking Prosthetic Foot 4.0, during walking at different speeds, using physiological determinants in transtibial and transfemoral amputees. Study design: Nonrandomized crossover design for amputees. Methods: Six able-bodied subjects, six unilateral transtibial amputees, and six unilateral transfemoral amputees underwent a 6-min walk test at normal speed, followed by series of 2-min walking at slow, normal, and fast speeds. The intensity of effort and subjective measures were determined. Amputees performed all walking tests on a treadmill with current and novel prostheses. Shapiro–Wilk normality tests and parametric and nonparametric tests were conducted (p < 0.05). Results: Compared to able-bodied individuals, the rating of perceived exertion levels were significantly elevated in transtibial and transfemoral amputees for both prostheses (p ≤ 0.016). Compared to able-bodied individuals transfemoral amputees also showed significantly elevated heart rate for both prostheses at normal speed (p ≤ 0.043). Within-group comparisons demonstrated that walking with Ankle Mimicking Prosthetic Foot significantly increased the heart rate in transfemoral amputees and transtibial compared to current prosthesis (p = 0.002). Furthermore, transfemoral amputees reached a significantly higher rating of perceived exertion levels. Conclusion: Intensity of effort during walking with Ankle Mimicking Prosthetic Foot is higher compared to current prostheses. Clinical relevance Ankle Mimicking Prosthetic Foot 4.0 is a novel quasi-passive ankle prosthesis with state-of-the-art technological parts. Subjective measures show the importance of this technology, but the intensity of effort during walking still remains higher compared to current passive prostheses, especially in transfemoral amputees.