Nicolas Berryman

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 Plyometric vs. Dynamic Weight Training on the Energy Cost of Running

Berryman, N, Maurel, D, and Bosquet, L. Effect of plyometric vs. dynamic weight training on the energy cost of running. J Strength Cond Res 24(7): 1818-1825, 2010-The purpose of this study is to compare the effects of 2 strength training methods on the energy cost of running (Cr). Thirty-five moderately to well-trained male endurance runners were randomly assigned to either a control group (C) or 2 intervention groups. All groups performed the same endurance-training program during an 8-week period. Intervention groups added a weekly strength training session designed to improve neuromuscular qualities. Sessions were matched for volume and intensity using either plyometric training (PT) or purely concentric contractions with added weight (dynamic weight training [DWT]). We found an interaction between time and group (p < 0.05) and an effect of time (p < 0.01) for Cr. Plyometric training induced a larger decrease of Cr (218 ± 16 to 203 ± 13 ml·kg−1·km−1) than DWT (207 ± 15 to 199 ± 12 ml·kg−1·km−1), whereas it remained unchanged in C. Pre-post changes in Cr were correlated with initial Cr (r = −0.57, p < 0.05). Peak vertical jump height (VJHpeak) increased significantly (p < 0.01) for both experimental groups (DWT = 33.4 ± 6.2 to 34.9 ± 6.1 cm, PT = 33.3 ± 4.0 to 35.3 ± 3.6 cm) but not for C. All groups showed improvements (p < 0.05) in Perf3000 (C = 711 ± 107 to 690 ± 109 seconds, DWT = 755 ± 87 to 724 ± 77 seconds, PT = 748 ± 81 to 712 ± 76 seconds). Plyometric training were more effective than DWT in improving Cr in moderately to well-trained male endurance runners showing that athletes and coaches should include explosive strength training in their practices with a particular attention on plyometric exercises. Future research is needed to establish the origin of this adaptation.

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.

Effects of combined physical and cognitive training on fitness and neuropsychological outcomes in healthy older adults.

Purpose Physical exercise and cognitive training have been shown to enhance cognition among older adults. However, few studies have looked at the potential synergetic effects of combining physical and cognitive training in a single study. Prior trials on combined training have led to interesting yet equivocal results. The aim of this study was to examine the effects of combined physical and cognitive interventions on physical fitness and neuropsychological performance in healthy older adults. Methods Seventy-six participants were randomly assigned to one of four training combinations using a 2×2 factorial design. The physical intervention was a mixed aerobic and resistance training program, and the cognitive intervention was a dual-task (DT) training program. Stretching and toning exercises and computer lessons were used as active control conditions. Physical and cognitive measures were collected pre- and postintervention. Results All groups showed equivalent improvements in measures of functional mobility. The aerobic–strength condition led to larger effect size in lower body strength, independently of cognitive training. All groups showed improved speed of processing and inhibition abilities, but only participants who took part in the DT training, independently of physical training, showed increased task-switching abilities. The level of functional mobility after intervention was significantly associated with task-switching abilities. Conclusion Combined training did not yield synergetic effects. However, DT training did lead to transfer effects on executive performance in neuropsychological tests. Both aerobic-resistance training and stretching-toning exercises can improve functional mobility in older adults.

Executive functions, physical fitness and mobility in well-functioning older adults

The objective of this study was to examine the relationships between executive functions, physical fitness and mobility in well-functioning older adults. Forty-eight well functioning older adults (70.5±5.3years old; 20 men, 28 women) were included in this study. Two median splits were conducted based on each individuals performance for the 10MWT and TUG. Comparisons between groups of slower and faster individuals were made with regard to executive functions and physical fitness parameters. A correlational approach was used to assess the association between variables. Between groups comparisons revealed that faster individuals in mobility tests demonstrate better performances in measures of cognitive flexibility (0.68<g<0.90). After including covariates from the medical/social domain, significant correlations were established between faster mobility tests and better cognitive flexibility (TUG: r=0.565; 10MWT: r=0.324). Between groups comparisons also revealed that faster individuals in mobility tests presented higher physical fitness levels (aerobic: 0.49<g<0.77, strength: 0.34<g<1.31). Significant correlations were found between better physical fitness and better cognitive flexibility (strength: r=-0.380; VO2 peak: r=-0.325) even after including age, education, fat-free mass and gender as covariates. These results suggest that the TUG and the 10MWT could potentially help distinguish individuals with poor neuromuscular, aerobic and cognitive flexibility performances.

Physical Functioning Is Associated With Processing Speed and Executive Functions in Community-Dwelling Older Adults

OBJECTIVES The aim of this study was to examine the association between physical functioning and cardiovascular burden on the cognitive performance of community-dwelling older adults. METHOD Ninety-three adults aged 60 and older completed a medical evaluation by a geriatrician, performance-based physical tests, and neuropsychological assessments. Cognitive composite scores (memory, speed, and executive) as well as a physical functioning score were created by averaging standardized z-scores of selected tests. A cardiovascular burden index was also computed by totalling the number of cardiovascular risk factors and diseases. RESULTS Multiple hierarchical regression analyses reveal that higher level of physical functioning was significantly associated with greater processing speed and better executive functions but was not associated with memory performance. These relations were independent of age, sex, and level of education. Cardiovascular burden was not significantly associated with any cognitive domain. DISCUSSION These results suggest that cognition is related to simple performance-based physical tests and highlight the importance of intervention studies aimed at enhancing cognitive and physical functioning in older adults.

Does Combined Physical and Cognitive Training Improve Dual-Task Balance and Gait Outcomes in Sedentary Older Adults?

Everyday activities like walking and talking can put an older adult at risk for a fall if they have difficulty dividing their attention between motor and cognitive tasks. Training studies have demonstrated that both cognitive and physical training regimens can improve motor and cognitive task performance. Few studies have examined the benefits of combined training (cognitive and physical) and whether or not this type of combined training would transfer to walking or balancing dual-tasks. This study examines the dual-task benefits of combined training in a sample of sedentary older adults. Seventy-two older adults (≥60 years) were randomly assigned to one of four training groups: Aerobic + Cognitive training (CT), Aerobic + Computer lessons (CL), Stretch + CT and Stretch + CL. It was expected that the Aerobic + CT group would demonstrate the largest benefits and that the active placebo control (Stretch + CL) would show the least benefits after training. Walking and standing balance were paired with an auditory n-back with two levels of difficulty (0- and 1-back). Dual-task walking and balance were assessed with: walk speed (m/s), cognitive accuracy (% correct) and several mediolateral sway measures for pre- to post-test improvements. All groups demonstrated improvements in walk speed from pre- (M = 1.33 m/s) to post-test (M = 1.42 m/s, p < 0.001) and in accuracy from pre- (M = 97.57%) to post-test (M = 98.57%, p = 0.005).They also increased their walk speed in the more difficult 1-back (M = 1.38 m/s) in comparison to the 0-back (M = 1.36 m/s, p < 0.001) but reduced their accuracy in the 1-back (M = 96.39%) in comparison to the 0-back (M = 99.92%, p < 0.001). Three out of the five mediolateral sway variables (Peak, SD, RMS) demonstrated significant reductions in sway from pre to post test (p-values < 0.05). With the exception of a group difference between Aerobic + CT and Stretch + CT in accuracy, there were no significant group differences after training. Results suggest that there can be dual-task benefits from training but that in this sedentary sample Aerobic + CT training was not more beneficial than other types of combined training.

Physiological Interpretation of the Slope during an Isokinetic Fatigue Test

To assess the relationship between selected measures (the slope and average performance) obtained during a high intensity isokinetic fatigue test of the knee (FAT) and relevant measures of anaerobic and aerobic capacities. 20 well-trained cyclists performed 3 randomly ordered sessions involving a FAT consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°.s−1, a maximal continuous graded exercise test (GXT), and a Wingate anaerobic test (WAnT). The slope calculated from peak torque (PT) and total work (TW) of knee extensors was highly associated to maximal PT (r=−0.86) and maximal TW (r=−0.87) measured during FAT, and moderately associated to peak power output measured during the WAnT (r=−0.64 to −0.71). Average PT and average TW were highly associated to maximal PT (r=0.93) and maximal TW (r=0.96), to mean power output measured during WAnT (r=0.83–0.90) and moderately associated to maximal oxygen uptake (0.58–0.67). In conclusion, the slope is mainly determined by maximal anaerobic power, while average performance is a composite measure depending on both aerobic and anaerobic energy systems according to proportions that are determined by the duration of the test.