Christophe Delecluse

Effect of 6‐Month Whole Body Vibration Training on Hip Density, Muscle Strength, and Postural Control in Postmenopausal Women: A Randomized Controlled Pilot Study

High‐frequency mechanical strain seems to stimulate bone strength in animals. In this randomized controlled trial, hip BMD was measured in postmenopausal women after a 24‐week whole body vibration (WBV) training program. Vibration training significantly increased BMD of the hip. These findings suggest that WBV training might be useful in the prevention of osteoporosis.

Strength Increase after Whole-Body Vibration Compared with Resistance Training

PURPOSE The aim of this study was to investigate and to compare the effect of a 12-wk period of whole-body vibration training and resistance training on human knee-extensor strength. METHODS Sixty-seven untrained females (21.4 +/- 1.8 yr) participated in the study. The whole-body vibration group (WBV, N = 18) and the placebo group (PL, N = 19) performed static and dynamic knee-extensor exercises on a vibration platform. The acceleration of the vibration platform was between 2.28 g and 5.09 g, whereas only 0.4 g for the PL condition. Vibration (35-40 Hz) resulted in increased EMG activity, but the EMG signal remained unchanged in the PL condition. The resistance-training group (RES, N = 18) trained knee extensors by dynamic leg-press and leg-extension exercises (10-20 RM). All training groups exercised 3x wk-1. The control group (CO, N = 12) did not participate in any training. Pre- and postisometric, dynamic, and ballistic knee-extensor strength were measured by means of a motor-driven dynamometer. Explosive strength was determined by means of a counter-movement jump. RESULTS Isometric and dynamic knee-extensor strength increased significantly (P < 0.001) in both the WBV group (16.6 +/- 10.8%; 9.0 +/- 3.2%) and the RES group (14.4 +/- 5.3%; 7.0 +/- 6.2%), respectively, whereas the PL and CO group showed no significant (P > 0.05) increase. Counter-movement jump height enhanced significantly (P < 0.001) in the WBV group (7.6 +/- 4.3%) only. There was no effect of any of the interventions on maximal speed of movement, as measured by means of ballistic tests. CONCLUSIONS WBV, and the reflexive muscle contraction it provokes, has the potential to induce strength gain in knee extensors of previously untrained females to the same extent as resistance training at moderate intensity. It was clearly shown that strength increases after WBV training are not attributable to a placebo effect.

Whole-Body-Vibration Training Increases Knee-Extension Strength and Speed of Movement in Older Women

Objectives: To investigate the effects of 24 weeks of whole‐body‐vibration (WBV) training on knee‐extension strength and speed of movement and on counter‐movement jump performance in older women.

WHOLE-BODY-VIBRATION-INDUCED INCREASE IN LEG MUSCLE ACTIVITY DURING DIFFERENT SQUAT EXERCISES

This study analyzed leg muscle activity during whole-body vibration (WBV) training. Subjects performed standard unloaded isometric exercises on a vibrating platform (Power Plate): high squat (HS), low squat (LS), and 1-legged squat (OL). Muscle activity of the rectus femoris, vastus lateralis, vastus medialis, and gastrocnemius was recorded in 15 men (age 21.2 ± 0.8 years) through use of surface electromyography (EMG). The exercises were performed in 2 conditions: with WBV and without (control [CO]) a vibratory stimulus of 35 Hz. Muscle activation during WBV was compared with CO and with muscle activation during isolated maximal voluntary contractions (MVCs). Whole-body vibration resulted in a significantly higher (p < 0.05) EMG root-mean-square compared with CO in all muscle groups and all exercises (between 139.9 ± 17.5% and 1360.6 ± 57.5%). The increase in muscle activity caused by WBV was significantly higher (p < 0.05) in OL compared with HS and LS. In conclusion, WBV resulted in an increased activation of the leg muscles. During WBV, leg muscle activity varied between 12.6 and 82.4% of MVC values.

Influence of high-resistance and high-velocity training on sprint performance

The purpose of this study is to analyze the effect of high-resistance (HR) and high-velocity (HV) training on the different phases of 100-m sprint performance. Two training groups (HR and HV) were compared with two control groups (RUN and PAS). The HR (N = 22) and HV group (N = 21) trained 3 d.wk-1 for 9 wk: two strength training sessions (HR or HV) and one running session. There was a run control group (RUN, N = 12) that also participated in the running sessions (1 d.wk-1) and a passive control group (PAS, N = 11). Running speed over a 100-m sprint was recorded every 2 m. By means of a principal component analysis on all speed variables, three phases were distinguished: initial acceleration (0-10 m), building-up running speed to a maximum (10-36 m), and maintaining maximum speed in the second part of the run (36-100 m). HV training resulted in improved initial acceleration (P < 0.05 compared with RUN, PAS, and HR), a higher maximum speed (P < 0.05 compared with PAS), and a decreased speed endurance (P < 0.05 compared to RUN and PAS). The HV group improved significantly in total 100 m time (P < 0.05 compared with the RUN and PAS groups). The HR program resulted in an improved initial acceleration phase (P < 0.05 compared with PAS).

Influence of strength training on sprint running performance current findings and implications for training

SummaryToday, it is generally accepted that sprint performance, like endurance performance, can improve considerably with training. Strength training, especially, plays a key role in this process. Sprint performance will be viewed multidimensionally as an initial acceleration phase (0 to 10m), a phase of maximum running speed (36 to 100m) and a transition phase in between. Immediately following the start action, the powerful extensions of the hip, knee and ankle joints are the main accelerators of body mass. However, the hamstrings, the m. adductor magnus and the m. gluteus maximus are considered to make the most important contribution in producing the highest levels of speed. Different training methods are proposed to improve the power output of these muscles. Some of them aim for hypertrophy and others for specific adaptations of the nervous system. This includes general (hypertrophy and neuronal activation), velocity specific (speed-strength) and movement specific (sprint associated exercises) strength training. In developing training strategies, the coach has to keep in mind that strength, power and speed are inherently related to one another, because they are all the output of the same functional systems. As heavy resistance training results in a fibre type IIb into fibre type IIa conversion, the coach has to aim for an optimal balance between sprint specific and nonspecific training components. To achieve this they must take into consideration the specific strength training demands of each individual, based on performance capacity in each specific phase of the sprint.

Effects of whole body vibration training on cardiorespiratory fitness and muscle strength in older individuals (A 1-year randomised controlled trial)

BACKGROUND whole body vibration (WBV) training appears to be an efficient alternative for conventional resistance training in older individuals. So far, no data exist about the vibratory effect on cardiorespiratory fitness. OBJECTIVES this randomised controlled trial assessed the effects of 1-year WBV training on cardiorespiratory fitness and muscle strength in community-dwelling adults over the age of 60. METHODS a total of 220 adults (mean age 67.1 years) were randomly assigned to a WBV group, fitness group or control group. The WBV group exercised on a vibration platform, and the fitness group performed cardiovascular, resistance, balance and stretching exercises. The control group did not participate in any training. Heart rate was measured during a single WBV session. Peak oxygen uptake (VO(2peak)) and time-to-peak exercise (TPE) were measured during progressive bicycle ergometry. Muscle strength was assessed by a dynamometer. RESULTS heart rate increased significantly during WBV training. After 1 year, VO(2peak), TPE and muscle strength increased significantly in the WBV and fitness groups. Both training groups improved similarly in VO(2peak) and muscle strength. The fitness group improved significantly more in TPE than the WBV group. CONCLUSION WBV training in community-dwelling elderly appears to be efficient to improve cardiorespiratory fitness and muscle strength.

Sedentary behaviour, physical activity and a continuous metabolic syndrome risk score in adults.

Objective:The association of sedentary behaviour and leisure time physical activity with a validated continuous metabolic syndrome risk score was investigated in adults.Subjects/Methods:A number of 992 adults (559 men) without cardiovascular disease or diabetes. Subjects reported time spent in leisure time physical activity and television watching/computer activities. A validated metabolic syndrome risk score, based on waist circumference, triglycerides, blood pressure, fasting plasma glucose and high-density lipoprotein cholesterol, was used. The metabolic syndrome risk score and time spent in sedentary behaviour and physical activity were analysed as continuous variables using multiple linear regression.Results:Metabolic syndrome risk was positively associated with time spent watching television/computer activities, irrespective of physical activity level, and after adjustment for age, education level, smoking status and dietary intake in women aged ⩾45 years (β=0.184, P<0.05). Independent of the time being sedentary, moderate to vigorous leisure time physical activity was inversely associated with metabolic syndrome risk in men (<45 years: β=−0.183, P<0.01; ⩾45 years: β=−0.192, P<0.01) and women aged ⩾45 years (β=−0.203, P<0.01).Conclusions:Although cross-sectional, the present results support inclusion of efforts to decrease sedentary behaviour in metabolic syndrome prevention strategies for women aged ⩾45 years, besides promotion of moderate to vigorous physical activity, since both behavioural changes might show additional effects.

The effects of whole-body vibration training and vitamin D supplementation on muscle strength, muscle mass, and bone density in institutionalized elderly women: A 6-month randomized, controlled trial

Sarcopenia and osteoporosis represent a growing public health problem. We studied the potential benefit of whole‐body vibration (WBV) training given a conventional or a high dose of daily vitamin D supplementation in improving strength, muscle mass, and bone density in postmenopausal women. In a 2 × 2 factorial‐design trial, 113 institutionalized elderly females aged over 70 years (mean age 79.6 years) were randomly assigned either to a WBV or a no‐training group, receiving either a conventional dose (880 IU/day) or a high dose (1600 IU/day) of vitamin D3. The primary aim was to determine the effects of 6 months of WBV and/or vitamin D supplementation on isometric and dynamic strength, leg muscle mass, and hip bone mineral density (BMD). Additionally, the increase in 25‐hydroxyvitamin D [25(OH)D] levels between conventional and high‐dose supplementation was compared. After 6 months of treatment, dynamic muscle strength, hip BMD, and vitamin D serum levels improved significantly in all groups, whereas isometric strength and muscle mass did not change. When compared with no training, the WBV program did not result in additional improvements. When compared with 880 IU, a high dose of 1600 IU of vitamin D did result in higher serum vitamin D levels but did not result in additional improvements. In institutionalized women older than 70 years, the WBV training protocol tested is not more efficient in enhancing muscle mass, strength, and hip BMD compared with vitamin D supplementation. A higher dose of 1600 IU of vitamin D does not provide additional musculoskeletal benefit in this population compared with conventional doses.

Effectiveness of a lifestyle intervention and a structured exercise intervention in older adults

OBJECTIVE To evaluate the effects of a lifestyle intervention and a structured exercise intervention on physical activity in older adults. METHOD Participants were randomly assigned to a lifestyle intervention (n=60), including an individualized home-based program supported by phone calls, or to a structured intervention (n=60) consisting of three weekly supervised sessions. Results were compared with a control group (n=66). Physical activity was measured with self-report questionnaires, pedometers, and accelerometers before the start (pretest), at the end (11 months, posttest), and after 23 months (follow-up). The study took place in Belgium from March 2004 until April 2006. RESULTS At posttest, both intervention groups had significantly increased their total physical activity compared with the control group. At follow-up, the lifestyle group showed significantly larger increases in active transportation and total steps than the control and structured group respectively. There were no longer significant differences between the structured intervention and the control group. CONCLUSIONS The structured and lifestyle interventions were equally effective at the end of the intervention. One year after the intervention the lifestyle group maintained a significant increase in physical activity, which highlights the potential of lifestyle programs in the battle against inactivity in older adults.