Olivier Seynnes

Effects of a physical activity program on postural stability in older people

Background and aims: The objective of this non-randomized study was to determine the influence of a specific physical activity program on the postural stability of older people. Methods: Seventy-four subjects (72.4±0.7 yrs) participated in an individualized three-month physical activity program designed to improve posture, balance and mobility — the PBM program. Sessions were held twice weekly. Postural stability was assessed using a force platform, subjects being in static and dynamic conditions, and with open and closed eyes. Changes in stabilometric parameters (Sway area, ML mean, AP mean, Total length, ML length and AP length) of the intervention group were compared to those of 14 control subjects (71.8±1.5 years). Results: A two-way analysis of variance with repeated measures did not show any significant post-program change in postural stability in the hard floor condition. In contrast, Sway area (p<0.0005), Total length (p<0.001) and AP length (p<0.01) were significantly reduced after the training program in the foam floor condition, with open and closed eyes. In addition, in the mediolateral axis condition and with closed eyes, AP length in the intervention group was significantly reduced (p<0.01, and in the antero-posterior axis condition with both open and closed eyes, Sway area (p<0.0005), Total length (p<0.0005) and AP length (p<0.05) decreased significantly. Conclusions: As shown by the results in the foam floor and dynamic conditions, our individualized physical activity program improved the postural stability of older people when the standing position was challenged. However, the lack of significant results for the hard floor condition suggests that three months is not sufficient to improve static balance. The PBM physical activity program can be used for balance training in older people, but further studies are required to determine the time needed to effect improvements in static balance in this population.

Effects of Increased Loading on In Vivo Tendon Properties: A Systematic Review.

ABSTRACT In vivo measurements have been used in the past two decades to investigate the effects of increased loading on tendon properties, yet the current understanding of tendon macroscopic changes to training is rather fragmented, limited to reports of tendon stiffening, supported by changes in material properties and/or tendon hypertrophy. The main aim of this review was to analyze the existing literature to gain further insights into tendon adaptations by extracting patterns of dose-response and time-course. PubMed/Medline, SPORTDiscus, and Google Scholar databases were searched for studies examining the effect of training on material, mechanical, and morphological properties via longitudinal or cross-sectional designs. Thirty-five of 6440 peer-reviewed articles met the inclusion criteria. The key findings were i) the confirmation of a nearly systematic adaptation of tendon tissue to training, ii) the important variability in the observed changes in tendon properties between and within studies, and iii) the absence of a consistent incremental pattern regarding the dose-response or the time-course relation of tendon adaptation within the first months of training. However, long-term (years) training was associated with a larger tendon cross-sectional area, without any evidence of differences in material properties. Our analysis also highlighted several gaps in the existing literature, which may be addressed in future research. In line with some cross-species observations about tendon design, tendon cross-sectional area allegedly constitutes the ultimate adjusting parameter to increased loading. We propose here a theoretical model placing tendon hypertrophy and adjustments in material properties as parts of the same adaptive continuum.Supplemental digital content is available in the text.

Effets de l’obésité sur la régulation posturale d’adolescentes. Étude préliminaire

Resume Objectif. – Le but de cette etude est de definir l’influence de l’obesite sur les valeurs de regulations posturales statiques d’adolescentes. Methode. – Neuf sujets obeses et sept non obeses ont ete caracterises par les parametres stabilometriques de surface, de longueur et position moyenne du centre de pression plantaire (CPP) dans les deux axes anteroposterieur et mediolateral. L’examen est repete 2 fois, les yeux ouverts puis les yeux fermes, dans les deux situations sans et avec un support en mousse. Resultats. – Des differences significatives de longueur sont observees entre les deux groupes en condition les yeux ouverts (p Conclusion. – Lorsque le sujet est soumis a une perturbation externe, une surcharge ponderale semble etre un facteur perturbateur du controle postural chez des adolescentes obeses. L’influence de la repartition de la masse grasse sur la regulation posturale n’a pu etre mise en evidence.

Adapted physical activity in old age: Effects of a low-intensity training program on isokinetic power and fatigability

Background and aims: This pilot study measured the effects of an original low-intensity training program, called “posture-balancing-mobility” (PBM), on muscular function. Methods: Nine non-disabled, elderly (74.3±6 years) subjects were trained with the PBM technique for 11 weeks (2 sessions per week). Mean power and fatigue index parameters were measured using an isokinetic dynamometer before and after training and compared with those recorded in another group of 9 elderly (71.1±4.3 years) subjects, who had performed aquatic exercises during the same period and with the same frequency. Results: The mean power of the knee extension muscles increased slightly but significantly on the dominant (15.6%, p<0.05) and non-dominant sides (13.4%, p<0.05) in the PBM group, with no significant fatigue index variation. None of the parameters changed significantly for the aquatic group, and comparison of variations obtained in the two groups showed no significant difference between their respective effects. Conclusions: Although the results showed slightly enhanced strength production in the PBM group, the low statistical power does not allow conclusions about the impact of this type of training intervention in its current form. Nevertheless, this pilot study provides some indication of the benefits that can be obtained from such an individualized approach. Its efficiency would most likely be improved by further exploration of the minimal threshold of intensity required for strength exercises and by measurement of its effect on functions involving neuromuscular parameters, such as balance or gait.

Training Strategies to Improve Muscle Power: Is Olympic-style Weightlifting Relevant?

Introduction This efficacy study investigated the effects of 1) Olympic-style weightlifting (OWL), 2) motorized strength and power training (MSPT), and 3) free weight strength and power training (FSPT) on muscle power. Methods Thirty-nine young athletes (20 ± 3 yr; ice hockey, volleyball, and badminton) were randomized into the three training groups. All groups participated in two to three sessions per week for 8 wk. The MSPT and FSPT groups trained using squats (two legs and single leg) with high force and high power, whereas the OWL group trained using clean and snatch exercises. MSPT was conducted as slow-speed isokinetic strength training and isotonic power training with augmented eccentric load, controlled by a computerized robotic engine system. FSPT used free weights. The training volume (sum of repetitions × kg) was similar between all three groups. Vertical jumping capabilities were assessed by countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), and loaded CMJ (10–80 kg). Sprinting capacity was assessed in a 30-m sprint. Secondary variables were squat one-repetition maximum (1RM), body composition, quadriceps thickness, and architecture. Results OWL resulted in trivial improvements and inferior gains compared with FSPT and MSPT for CMJ, SJ, DJ, and 1RM. MSPT demonstrated small but robust effects on SJ, DJ, loaded CMJ, and 1RM (3%–13%). MSPT was superior to FSPT in improving 30-m sprint performance. FSPT and MSPT, but not OWL, demonstrated increased thickness in the vastus lateralis and rectus femoris (4%–7%). Conclusions MSPT was time-efficient and equally or more effective than FSPT training in improving vertical jumping and sprinting performance. OWL was generally ineffective and inferior to the two other interventions.