Balance Performance across the Lifespan Assessed by the Leonardo Mechanograph®: A Cross-Sectional Study.

Reference values of sway parameters have not been published for the Leonardo mechanograph® so far. The aim of this cross-sectional study was to determine normative values on postural control measured by the force plate Leonardo Mechanograph® and to analyze the influence of age and sex on balance performance. A set of standardized standing positions with eyes opened (Romberg, semi-tandem, tandem, unipedal standing) was carried out. Analysis of covariance (ANCOVA) was used to detect age-and sex-related differences in center of pressure (COP) parameters (path length, velocity, elliptical area, anterior-posterior, and medio-lateral directions). Measurements were available for 570 subjects aged 20-86 years. Statistical analysis showed a high effect of age group on postural control (partial n² between 0.1 and 0.4) with a U-shaped dependency between postural control and age for all area- and path-related COP parameters, with the largest sway in the youngest (aged 20-40) and the oldest age group (aged 60-86). For velocity of COP, a linear deterioration with increasing age was found. Medio-lateral components of COP are likely to indicate the extent of postural control. Significant sex differences were not clearly supported by current findings. Age- and sex-related normative values are a useful resource for diagnostic, research, and training.

Hypertrophy and Explosive-Reactive Functioning in Sedentary Men After 10 Weeks of Whole-Body Vibration.

Ebing, J, Gast, U, Hauptmann, C, Felsenberg, D, and Belavý, DL. Hypertrophy and explosive-reactive functioning in sedentary men after 10 weeks of whole-body vibration. J Strength Cond Res 32(1): 27-36, 2018-The objective of this study was to determine the impact of vertical (Power-plate; POW) and side-alternating (Galileo; GAL) whole-body vibration exercise on muscle mass and lower-limb neuromuscular function. Forty-three sedentary male subjects (18-30 year) randomized into 3 groups underwent 2 upper-body exercise sessions per week for 10 weeks. Two groups of subjects underwent additional squat exercises on the GAL (N = 15) or POW (N = 14) devices. The third group was control. On magnetic resonance imaging, volume of the thigh muscles was measured. Countermovement jump, multiple one-leg hopping, drop jump, landing test, 15-m sprint, and grip strength were performed. Measurements were performed at baseline, and at 5 and 10 weeks. Significantly greater increases in vasti volume were seen in the GAL (+4.15%; p = 0.00076 vs. control) and POW (+4.81%; p = 0.0074 vs. control) groups than in the control group (-1.22%) at 10 weeks. The adductor magnus volume increased in the GAL (+2.24%; p = 0.00038 vs. baseline) and POW (+2.33%; p = 0.00038 vs. baseline) groups at 10 weeks, but this was not significantly different from the control (-0.67%; p = 0.54 vs. baseline). Hamstring volume decreased in GAL (-1.85%; p = 0.00038 vs. baseline) at 5 weeks with the reduction in the POW group at 5 weeks (-1.73%; p = 0.17 vs. baseline) not reaching significance. There were no significant differences between the POW and GAL groups (p ≥ 0.084) and no significant changes in neuromuscular performance. Twice weekly squat exercises with whole-body vibration, progressing from 3- to 5-minute time under tension, lead to thigh muscle hypertrophy but no improvements in explosive-reactive function.

Exercise and Transversus Abdominis Muscle Atrophy after 60-d Bed Rest.

PURPOSE: This study aimed to investigate atrophy in the deep abdominal muscles, spinal extensors, and the effect of high-load resistive exercise with and without whole-body vibration after 60 d of strict bed rest. METHODS: Twenty-four subjects underwent 60 d of head-down tilt bed rest and performed either resistive vibration exercise (RVE), resistive exercise only (RE), or no exercise control (2nd Berlin BedRest Study). The thickness of the transversus abdominis, internal oblique, and erector spinae muscles and the area of the multifidus muscle were measured bilaterally via real-time ultrasound. Intention-to-treat analysis was implemented, and P values were adjusted by the false discovery rate method. RESULTS: At the end of the bed rest, transversus abdominis thickness was reduced by 18.3% in the inactive group (P = 0.00011) with no significant change in the RVE (-4.0%; P = 0.014 vs control) or RE (-5.0%; P = 0.10 vs control) groups. In the inactive subjects, internal oblique thickness reduced by 10.6% (P = 0.0025) and by 7% (P > 0.05) in each of the training groups. The lengthening of the lumbar spine was greatest on day 1 (+7.4%, P = 0.004) and day 2 (+6.3%, P = 0.004; day 54: +4.1%, P = 0.023). A 4.7% reduction of multifidus area was observed on day 1 of bed rest (P = 0.0049) and a 4.2% reduction of erector spinae thickness was observed on day 2 (P = 0.0011). Extensor atrophy and spinal lengthening was not affected by exercise. No significant difference was seen between RVE and RE. CONCLUSION: Bed rest leads to atrophy of the transversus abdominis and internal oblique muscles. The exercise program, which implemented lower-limb and back extension exercises against shoulder restraints, was able to reduce atrophy seen in transversus abdominis in bed rest.

Muscle atrophy, pain, and damage in bed rest reduced by resistive (vibration) exercise.

UNLABELLED: The purpose of this study was to investigate the effectiveness of a short-duration (5-6 min, 3 d·wk) resistive exercise program with (RVE) or without (RE) whole-body vibration in reducing muscle atrophy in the lower limb during prolonged inactivity when compared with that in an inactive control group. METHODS: As part of the second Berlin BedRest Study, 24 male subjects underwent 60 d of head-down tilt bed rest. Using magnetic resonance imaging, muscle volumes of the individual muscles of the lower limb were calculated before and at various intervals during and after bed rest. Pain levels and markers of muscle damage were also evaluated during and after bed rest. Adjustment of P values to guard against false positives was performed via the false discovery rate method. RESULTS: On the "intent-to-treat" analysis, RE reduced atrophy of the medial and lateral gastrocnemius, soleus, vasti, tibialis posterior, flexor hallucis longus, and flexor digitorum longus (P ≤ 0.045 vs control group) and RVE reduced atrophy of the medial and lateral gastrocnemius and tibialis posterior (P ≤ 0.044). Pain intensity reports after bed rest were lower in RE at the foot (P ≤ 0.033) and whole lower limb (P = 0.01) and in RVE at the thigh (P ≤ 0.041), lower leg (P ≤ 0.01), and whole lower limb (P ≤ 0.036). Increases in sarcomere-specific creatine kinase after bed rest were less in RE (P = 0.020) and RVE (P = 0.020). No differences between RE and RVE were observed. CONCLUSIONS: In conclusion, a short-duration RVE or RE can be effective in reducing the effect of prolonged bed rest on lower extremity muscle volume loss during bed rest and muscle damage and pain after bed rest.

In vivo measurements of the effect of whole body vibration on spinal loads.

PURPOSE: It is assumed that whole body vibration (WBV) improves muscle strength, bone density, blood flow and mobility and is therefore used in wide ranges such as to improve fitness and prevent osteoporosis and back pain. It is expected that WBV produces large forces on the spine, which poses a potential risk factor for the health of the spine. Therefore, the aim of the study was to measure the effect of various vibration frequencies, amplitudes, device types and body positions on the loads acting on a lumbar vertebral body replacement (VBR). METHODS: Three patients suffering from a fractured lumbar vertebral body were treated using a telemeterized VBR. The implant loads were measured during WBV while the patients stood on devices with vertically and seesaw-induced vibration. Frequencies between 5 and 50 Hz and amplitudes of 1, 2 and 4 mm were tested. The patients stood with their knees straight, slightly bent, or bent at 60°. In addition, they stood on their forefeet. RESULTS: The peak resultant forces on the implant increased due to vibration by an average of 24% relative to the forces induced without vibration. The average increase of the peak implant force was 27% for vertically induced vibration and 15% for seesaw vibration. The forces were higher when the legs were straight than when the knees were bent. Both the vibration frequency and the amplitude had only a minor effect on the measured forces. CONCLUSIONS: The force increase due to WBV is caused by an activation of the trunk muscles and by the acceleration forces. The forces produced during WBV are usually lower than those produced during walking. Therefore, the absolute magnitude of the forces produced during WBV should not be harmful, even for people with osteoporosis.

Progressive adaptation in physical activity and neuromuscular performance during 520d confinement.

To understand whether prolonged confinement results in reductions in physical activity and adaptation in the musculoskeletal system, six subjects were measured during 520 d isolation in the Mars500 study. We tested the hypothesis that physical activity reduces in prolonged confinement and that this would be associated with decrements of neuromuscular performance. Physical activity, as measured by average acceleration of the body's center of mass ("activity temperature") using the actibelt® device, decreased progressively over the course of isolation (p<0.00001). Concurrently, countermovement jump power and single-leg hop force decreased during isolation (p<0.001) whilst grip force did not change (p≥0.14). Similar to other models of inactivity, greater decrements of neuromuscular performance occurred in the lower-limb than in the upper-limb. Subject motivational state increased non-significantly (p = 0.20) during isolation, suggesting reductions in lower-limb neuromuscular performance were unrelated to motivation. Overall, we conclude that prolonged confinement is a form of physical inactivity and is associated with adaptation in the neuromuscular system.

Short-duration resistive exercise sustains neuromuscular function after bed rest.

PURPOSE: The study's purpose was to assess the effectiveness of a short-duration three-times-weekly high-load resistive exercise program on preventing deterioration in neuromuscular function after prolonged bed rest. METHODS: Twenty-four male subjects performed high-load resistive exercise (n = 8), high-load resistive exercise with whole-body vibration (n = 9), or no exercise (control, n = 9) during 60-d head-down tilt bed rest as part of the 2nd Berlin Bed Rest Study. Peak countermovement jump power and height, sit-to-stand performance, sprint time over 15 and 30 m, and leg press one-repetition maximum were measured before and after bed rest. RESULTS: The exercise interventions were capable of ameliorating losses of peak countermovement jump power (P < 0.001) and height (P < 0.001), deterioration of sit-to-stand time from 45-cm (P = 0.034) and 30-cm (P < 0.001) sitting positions, increases of 15-m (P = 0.037) and 30-m (P = 0.005) sprint time, and losses of leg press one-repetition maximum (P < 0.001). CONCLUSIONS: The short-duration (6-min time under tension per training session) exercise countermeasure program performed three times a week was capable of reducing the effect of prolonged bed rest on many neuromuscular function measures.

Countermeasures against lumbar spine deconditioning in prolonged bed rest: resistive exercise with and without whole body vibration.

To evaluate the effect of short-duration, high-load resistive exercise, with and without whole body vibration on lumbar muscle size, intervertebral disk and spinal morphology changes, and low back pain (LBP) incidence during prolonged bed rest, 24 subjects underwent 60 days of head-down tilt bed rest and performed either resistive vibration exercise (n = 7), resistive exercise only (n = 8), or no exercise (n = 9; 2nd Berlin Bed-Rest Study). Discal and spinal shape was measured from sagittal plane magnetic resonance images. Cross-sectional areas (CSAs) of the multifidus, erector spinae, quadratus lumborum, and psoas were measured on para-axial magnetic resonance images. LBP incidence was assessed with questionnaires at regular intervals. The countermeasures reduced CSA loss in the multifidus, lumbar erector spinae and quadratus lumborum muscles, with greater increases in psoas muscle CSA seen in the countermeasure groups (P ≤ 0.004). There was little statistical evidence for an additional effect of whole body vibration above resistive exercise alone on these muscle changes. Exercise subjects reported LBP more frequently in the first week of bed rest, but this was only significant in resistive exercise only (P = 0.011 vs. control, resistive vibration exercise vs. control: P = 0.56). No effect of the countermeasures on changes in spinal morphology was seen (P ≥ 0.22). The results suggest that high-load resistive exercise, with or without whole body vibration, performed 3 days/wk can reduce lumbar muscle atrophy, but further countermeasure optimization is required.

Prevention of bone loss during 56 days of strict bed rest by side-alternating resistive vibration exercise.

Bed rest is a recognized model for muscle atrophy and bone loss in space flight and in clinical medicine. We hypothesized that whole body vibration in combination with resistive exercise (RVE) would be an effective countermeasure. Twenty healthy male volunteers underwent horizontal bed rest for 56 days and were randomly assigned either to a group that performed RVE 11 times per week or to a group that underwent bed rest only (Ctrl). Bone mineral content (BMC) was assessed by peripheral quantitative computed tomography (pQCT) in the tibia and the radius and by dual x-ray absorptiometry (DXA) in the hip and lumbar spine at baseline and at regular intervals during bed rest and a 12-month follow-up. RVE appeared to protect muscle size and function, and it also prevented bone loss (p-values between <0.001 and 0.01). Bone losses were largest in the distal tibia epiphysis, where BMC declined from 421.8 mg/mm (SD 51.3) to 406.6 mg/mm (SD 52.7) in Ctrl, but only from 411.1 mg/mm (SD 56.6) to 409.6 mg/mm (SD 66.7) in RVE. Most of the BMC losses were recovered by 12-month follow-up. Analyses showed that the epiphyseal cortex, rather than spongiosa, depicted the most pronounced changes during bed rest and recovery. These results suggest that the combined countermeasure applied in this study is effective to prevent bone losses from the tibia. This underlines the importance of mechanical usage for the maintenance of the human skeleton.