Olivier Dupuy

Higher levels of cardiovascular fitness are associated with better executive function and prefrontal oxygenation in younger and older women

Aim: Many studies have suggested that physical exercise training improves cognition and more selectively executive functions. There is a growing interest to clarify the neurophysiological mechanisms that underlie this effect. The aim of the current study was to evaluate the neurophysiological changes in cerebral oxygenation associated with physical fitness level and executive functions. Method: In this study, 22 younger and 36 older women underwent a maximal graded continuous test (i.e., V˙O2max) in order to classify them into a fitness group (higher vs. lower fit). All participants completed neuropsychological paper and pencil testing and a computerized Stroop task (which contained executive and non-executive conditions) in which the change in prefrontal cortex oxygenation was evaluated with near infrared spectroscopy (NIRS). Results: Our findings revealed a Fitness × Condition interaction (p < 0.05) such that higher fit women scored better on measures of executive functions than lower fit women. In comparison to lower fit women, higher fit women had faster reaction times in the Executive condition of the computerized Stroop task. No significant effect was observed in the non-executive condition of the test and no interactions were found with age. In measures of cerebral oxygenation (ΔHbT and ΔHbO2), we found a main effect of fitness on cerebral oxygenation during the Stroop task such that only high fit women demonstrated a significant increase in the right inferior frontal gyrus. Discussion/Conclusion: Higher fit individuals who demonstrate better cardiorespiratory functions (as measured by V˙O2max) show faster reaction times and greater cerebral oxygenation in the right inferior frontal gyrus than women with lower fitness levels. The lack of interaction with age, suggests that good cardiorespiratory functions can have a positive impact on cognition, regardless of age.

Reliability of heart rate measures used to assess post-exercise parasympathetic reactivation

Postexercise HRR (heart rate recovery) and HRV (heart rate variability) are commonly used to asses non‐invasive cardiac autonomic regulation and more particularly reactivation parasympathetic function. Unfortunately, the reliability of postexercise HRR and HRV remains poorly quantified and is still lacking. The aim of this study was to examine absolute and relative reliability of HRR and HRV indices used to assess postexercise cardiac parasympathetic reactivation.

Effect of overreaching on cognitive performance and related cardiac autonomic control.

The purpose of this study was to characterize the effect of a 2‐week overload period immediately followed by a 1‐week taper period on different cognitive processes including executive and nonexecutive functions, and related heart rate variability. Eleven male endurance athletes increased their usual training volume by 100% for 2 weeks, and decreased it by 50% for 1 week. A maximal graded test, a constant speed test at 85% of peak treadmill speed, and a Stroop task with the measurement of heart rate variability were performed at each period. All participants were considered as overreached. We found a moderate increase in the overall reaction time to the three conditions of the Stroop task after the overload period (816 ± 83 vs 892 ± 117 ms, P = 0.03) followed by a return to baseline after the taper period (820 ± 119 ms, P = 0.013). We found no association between cognitive performance and cardiac parasympathetic control at baseline, and no association between changes in these measures. Our findings clearly underscore the relevance of cognitive performance in the monitoring of overreaching in endurance athletes. However, contrary to our hypothesis, we did not find any relationship between executive performance and cardiac parasympathetic control.

A Comparison of 2 Optical Timing Systems Designed to Measure Flight Time and Contact Time During Jumping and Hopping

Bosquet, L, Berryman, N, and Dupuy, O. A comparison of 2 optical timing systems designed to measure flight time and contact time during jumping and hopping. J Strength Cond Res 23(9): 2660-2665, 2009-This study was designed to investigate the interchangeability of 2 commercial optical timing systems for measuring flight time and contact time during jumping and hopping. Seventy-three physical education students (33 men and 40 women) participated in this study. They were instructed to perform 3 jump protocols (squat jump, countermovement jump, and countermovement jump free arms) and a hopping test (10 seconds with straight legs at a frequency of 2 Hz). Flight time and contact time were measured with 2 optical timing systems (Optojump, Microgate, Italia and IR-mat, Ergotest, Sweden), consisting of 2 bars placed opposite to each other. Both systems trigger a timer with a precision of 1 millisecond each time the infrared light is interrupted by the feet. Jump height was given by the systems, whereas leg stiffness was computed from contact time and flight time. Flight time was higher when measured with the IR-mat (bias ± 95% LOA [limits of agreement] = 5 ± 14 ms, p < 0.001). This difference was trivial (effect size <0.2) and clinically meaningless. The high correlation between sets of data (r = 0.99) together with narrow 95% LOA (3%) support the interchangeability of both systems to measure flight time. Similar results were found with contact time (bias ± 95% LOA = 8 ± 23 ms, p < 0.001, effect size <0.2 and r = 0.99), with the exception that it was the Optojump that provided the higher values. These trivial but significant differences between both systems had minor impact on jumping height (bias ± 95% LOA = 0.6 ± 1.7 cm, p < 0.001), effect size <0.2 and r = 0.99), and stiffness (bias ± 95% LOA = 0.8 ± 1.4 N·m−1·kg−1, p < 0.001, effect size <0.2 and r = 0.98). We concluded that both systems can be used interchangeably.

Effect of training cessation on muscular performance: A meta‐analysis

The purpose of this study was to assess the effect of resistance training cessation on strength performance through a meta‐analysis. Seven databases were searched from which 103 of 284 potential studies met inclusion criteria. Training status, sex, age, and the duration of training cessation were used as moderators. Standardized mean difference (SMD) in muscular performance was calculated and weighted by the inverse of variance to calculate an overall effect and its 95% confidence interval (CI). Results indicated a detrimental effect of resistance training cessation on all components of muscular performance: [submaximal strength; SMD (95% CI) = −0.62 (−0.80 to −0.45), P < 0.01], [maximal force; SMD (95% CI) = −0.46 (−0.54 to −0.37), P < 0.01], [maximal power; SMD (95% CI) = −0.20 (−0.28 to −0.13), P < 0.01]. A dose–response relationship between the amplitude of SMD and the duration of training cessation was identified. The effect of resistance training cessation was found to be larger in older people (> 65 years old). The effect was also larger in inactive people for maximal force and maximal power when compared with recreational athletes. Resistance training cessation decreases all components of muscular strength. The magnitude of the effect differs according to training status, age or the duration of training cessation.

EFFECT OF INTERVAl TRAININg ON COgNITIVE FUNCTIONINg AND CEREBRAl OxygENATION IN OBESE PATIENTS: A PIlOT STUDy

OBJECTIVE To assess the effect of a 4-month high-intensity interval training programme on cognitive functioning, cerebral oxygenation, central haemodynamic and cardiometabolic parameters and aerobic capacity in obese patients. METHODS Cognitive functioning, cerebral oxygenation, central haemodynamic, cardiometabolic and exercise para-meters were measured before and after a 4-month high-intensity interval training programme in 6 obese patients (mean age 49 years (standard deviation 8), fat mass percentage 31 ± 7%). RESULTS Body composition (body mass, total and trunk fat mass, waist circumference) and fasting insulin were improved after the programme (p < 0.05). V. O2 and power output at ventilatory threshold and peak power output were improved after the programme (p < 0.05). Cognitive functioning, including short-term and verbal memory, attention and processing speed, was significantly improved after training (p < 0.05). Cerebral oxygen extraction was also improved after training (p < 0.05). CONCLUSION These preliminary results indicate that a 4-month high-intensity interval training programme in obese patients improved both cognitive functioning and cere-bral oxygen extraction, in association with improved exercise capacity and body composition.

Night and postexercise cardiac autonomic control in functional overreaching

The purpose of this study was to evaluate the effect of a 2-week overload period immediately followed by a 1-week taper period on the autonomic control of heart rate during the night or after exercise cessation. Eleven male endurance athletes increased their usual training volume by 100% for 2 weeks (overload) and decreased it by 50% for 1 week (taper). A maximal graded exercise test and a constant-speed test at 85% of peak treadmill speed, both followed by a 10-min passive recovery period, were performed at baseline and after each period. Heart rate variability was also measured during a 4-h period in the night or during estimated slow-wave sleep. All participants were considered to be overreached based on performance and physiological and psychological criteria. We found a decrease in cardiac parasympathetic control during slow-wave sleep (HFnu = 61.3% ± 11.7% vs 50.0% ± 10.1%, p < 0.05) but not during the 4-h period, as well as a faster heart rate recovery following the maximal graded exercise test (τ = 61.8 ± 14.5 s vs 54.7 ± 9.0 s, p < 0.05) but not after the constant-speed test, after the overload period. There was a return to baseline for both measures after the taper period. Other indices of cardiac autonomic control were not altered by the overload period. Care should be taken in selecting the most sensitive heart rate measures in the follow-up of athletes, because cardiac autonomic control is not affected uniformly by overload training.

Effect of Functional Overreaching on Executive Functions

The aim of this study was to investigate whether cognitive performance was a valid marker of overreaching. 10 well-trained male endurance athletes increased their training load by 100% for 2 weeks. They performed a maximal graded test, a constant speed test, a reaction time task and a computerized version of the Stroop color word-test before and after this overload period. Regarding performance results, five participants were considered as overreached and the five remaining were considered as well-trained. We found no significant differences between groups in performing the Stroop test. Noteworthy, we found a small increase in response time in the more complex condition in overreached athletes (1 188+/-261 to 1 297+/-231 ms, effect size=0.44), while it decreased moderately in the well-trained athletes (1 066+/-175 to 963+/-171 ms, effect size=-0.59). Furthermore, we found an interaction between time and group on initiation time of the reaction time task, since it increased in overreached athletes after the overload period (246+/-24 to 264+/-26 ms, p<0.05), while it remained unchanged in well-trained participants. Participants made very few anticipation errors, whatever the group or the period (error rate <2%).We concluded that an unaccustomed increase in training volume which is accompanied by a decrement in physical performance induces a deterioration of some executive functions.

Cardiovascular and hemodynamic responses on dryland vs. immersed cycling

OBJECTIVES To investigate the effect of water immersion on oxygen uptake (VO2) and central hemodynamic responses during incremental maximal exercise at the same external power output (P ext) and recovery on an immersible ergocycle vs. a dryland ergocycle. DESIGN Cross-over design study. METHODS Twenty healthy participants (32 ± 7 years; 173 ± 6 cm; 71.7 ± 9.7 kg) performed maximal incremental exercise tests while pedalling either immersed on immersible ergocycle (Hydrorider(®)) or on dryland ergocycle (Ergoline 800 S; Bitz, Germany). Initial P ext of dryland ergocycle protocol was set at 25 W and increased by 25 W every minute until exhaustion. P ext on immersible ergocycle was controlled by pedalling rate (rpm). Initial rpm was set at 40 rpm and was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and central hemodynamic parameters were measured continuously during exercise and a 5-min recovery period. Reported VO2, stroke volume, cardiac output (Q) and arteriovenous difference (C(a-v)O2) were compared. RESULTS During exercise on immersible ergocycle, VO2 and C(a-v)O2 were lower (P < 0.0001) whereas stroke volume and Q were higher (P < 0.05) relative to a dryland ergocycle exercise of equivalent P ext. CONCLUSIONS During exercise and recovery in immersion, (VO2) and arteriovenous difference were reduced in healthy young participants, while stroke volume and cardiac output were increased for the same P ext. During the recovery, central hemodynamics responses remained higher in immersible ergocycle.

Comparable Cerebral Oxygenation Patterns in Younger and Older Adults during Dual-Task Walking with Increasing Load

The neuroimaging literature on dual-task gait clearly demonstrates increased prefrontal cortex (PFC) involvement when performing a cognitive task while walking. However, findings from direct comparisons of the cerebral oxygenation patterns of younger (YA) and older (OA) adults during dual-task walking are mixed and it is unclear how YA and OA respond to increasing cognitive load (difficulty) while walking. This functional near infra-red (fNIRS) study examined cerebral oxygenation of YA and OA during self-paced dual-task treadmill walking at two different levels of cognitive load (auditory n-back). Changes in accuracy (%) as well as oxygenated (HbO) and deoxygenated (HbR) hemoglobin were examined. For the HbO and HbR measures, eight regions of interest (ROIs) were assessed: the anterior and posterior dorsolateral and ventrolateral PFC (aDLPFC, pDLPFC, aVLPFC, pVLPFC) in each hemisphere. Nineteen YA (M = 21.83 years) and 14 OA (M = 66.85 years) walked at a self-selected pace while performing auditory 1-back and 2-back tasks. Walking alone (single motor: SM) and performing the cognitive tasks alone (single cognitive: SC) were compared to dual-task walking (DT = SM + SC). In the behavioural data, participants were more accurate in the lowest level of load (1-back) compared to the highest (2-back; p < 0.001). YA were more accurate than OA overall (p = 0.009), and particularly in the 2-back task (p = 0.048). In the fNIRS data, both younger and older adults had task effects (SM < DT) in specific ROIs for ΔHbO (three YA, one OA) and ΔHbR (seven YA, eight OA). After controlling for walk speed differences, direct comparisons between YA and OA did not reveal significant age differences, but did reveal a difficulty effect in HbO in the left aDLPFC (p = 0.028) and significant task effects (SM < DT) in HbR for six of the eight ROIs. Findings suggest that YA and OA respond similarly to manipulations of cognitive load when walking on a treadmill at a self-selected pace.