Effects of a short-term strength training programme on lymphocyte subsets at rest in elderly humans

The effects of a short-term strength training programme on resting lymphocyte subsets and stress hormone concentrations were analysed in 32 elderly sedentary subjects. Out of these 32 subjects, 8 women and 8 men [mean age 70.1 (SEM 1.0) years] were randomly assigned to a 8-week strength training programme which consisted of three sets of eight repetitions at 80% of one repetition maximum, for leg press, bilateral leg extension and seated chest press, 3 days a week. The remaining 8 women and 8 men [mean age 70.5 (SEM 0.9) years ] served as controls. Absolute counts of lymphocyte subsets (CD20+, CD3+, CD3+CD4+, CD3+CD8+, CD3?CD56+CD16+) were measured with a new technique combining fluorescent microspheres and flow cytometry. In the trained subjects, substantial increases in strength took place in one repetition maximum during the 8-week training period for leg press [from means of 20.7 (SEM 1.0) to 23.6 (SEM 1.0) N?·?kg^?1 _LBM (lean body mass)], chest press [from means of 5.4 (SEM 0.3) to 6.2 (SEM 0.3) N?·?kg^?1 _LBM] and bilateral leg extension [from means of 6.3 (SEM 0.2) to 7.4 (SEM 0.3) N?·?kg^?1 _LBM] movements. Baseline cortisol concentration (P?P?P?P?相似文献   

Physical inactivity and cognitive functioning: results from bed rest studies

In addition to multiple health benefits, participation in physical activity can enhance cognitive functioning. Less clear is how reducing physical activity levels affects cognition, an issue potentially addressed by bed rest studies having included cognitive tests. Detailed and reviewed here are 17 such studies, featuring 251 subjects, bed rest for 7–70 days, and tests of cognition ranging from reaction time to executive functions. The reported effects of bed rest on cognitive performance vary considerably, from a generally expected worsening to an improvement. Practice effects could be implicated in the performance improvements, and reports of worsening are often of limited interpretability or the results were not replicated. Any cognitive effects of bed rest thus remain to be established. Detrimental effects could influence the in-progress plans for human spaceflights to Mars (simulated by bed rest), and have implications for medical conditions promoting inactivity and lifestyles that are largely sedentary.

Effects of 20-day bed rest with and without strength training on postural sway during quiet standing

Aim: To examine the effect of unweighting as a possible contributory factor to a reduced calf muscle volume on postural sway during quiet standing, changes in postural sway following bed rest with or without strength training were investigated. Methods: Twelve young men participated in a 20‐day bed‐rest study. Subjects were divided into a non‐training group (BR‐Con) and a strength training group (BR‐Tr). For the BR‐Tr group, training was comprised of dynamic calf‐raise and leg‐press exercises to maintain the muscle volume of the plantar flexors. Before and after bed rest, subjects maintained quiet standing in a barefoot position on a force platform with their eyes open or closed. During the quiet stance, foot centre‐of‐pressure (CoP) and the mean velocity of CoP was calculated. Muscle volume of the plantar flexors was computed using axial magnetic resonance images of the leg. Results: After the bed‐rest period, the muscle volume decreased in the BR‐Con group but not in the BR‐Tr group. The mean velocity of CoP as an assessment of postural sway, however, increased in both groups. These results indicate that the strength training during bed rest cannot counteract the increase in postural sway. Conclusion: We concluded that postural sway increases following 20 days of bed rest despite maintenance of the muscle volume of plantar flexors as the main working muscles for the human postural standing.     

Effect of strict bed rest for 30 days on human water metabolism

The effect of strict bed rest for 30 days on the state of the water metabolism, the kinetics of water excretion, and the mean daily water loss was studied in man. Hypokinesia was found to reduce the rate of water renewal and to decrease the total water loss of the body. The relative water content as a percentage of body weight on the 25th day of hypokinesia was identical with the control.(Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 79, No. 2, pp. 23–25, February, 1975.     

Effects of head-down bed rest and artificial gravity on spatial orientation

We studied spatial orientation before and after 21 days of 6° head-down bed rest in 15 subjects. During bed rest, 8 subjects were treated daily with 1 h Gz centrifugation (artificial gravity) (2.5 g at the feet; 1.0 g at the heart), with 7 subjects serving as controls. Ocular counter-rolling and subjective visual vertical were assessed during 90° whole body roll tilt to the left and right. Ocular counter-rolling was unaffected by bed rest and bed rest + artificial gravity. Performance on the subjective visual vertical task was unchanged in the control group, but exhibited a significant increase in error for 48 h after bed rest in the treatment (artificial gravity) group. Intermittent application of linear acceleration along the long body axis may have increased the weighting of the idiotropic vector, resulting in an increased bias of the subjective visual vertical toward the long body axis during 90° roll tilt.     

Effects of short-term Huatou Chan training on health

Previous studies have shown that perennial Chan training leads to improvements in brain functioning. However, few studies have investigated the effects of short-term Huatou Chan training. The current study explored the effects of a three-day Huatou Chan training on physical and emotional health, as well as brain state. Seventy healthy subjects were recruited and divided into two groups: the Huatou Chan group and the Control group. The Huatou Chan group received a 3-day Huatou Chan training, while the Control group waited for three days. Both groups completed a 6 min Brain State Index recording, the SCL-90, the brief profile of mood state, the meaning in life questionnaire, and the Index of Well-being, prior to and after the training or waiting period. Results showed that short-term Huatou Chan training had significant benefits on some aspects such as physical and emotional health (obsessive-compulsive, depression, hostility, and psychoticism), negative emotions (tension-anxiety, depression-dejection, anger-hostility, fatigue-inertia, and confusion-bewilderment), well-being, and attitude towards life. In addition, short-term Chan training can significantly improve brain state, as shown by the index of depression, anxiety, alerting and intelligence. This is the first study to provide direct evidence for the benefits of short-term intensive Huatou Chan training on physical and mental health.     

Inactivity and muscle: effect of resistance training during bed rest on muscle size in the lower limb

The present study aimed to investigate the effect of dynamic leg press training on the physiological cross-sectional areas (PCSAs) of human lower limb muscles during 20 days of 6 degrees head-down tilt bed rest. Five healthy men comprised the resistance training group (BR-Tr) and data from two previous studies were used to derive a 10-man control group (BR-Cont). The BR-Tr performed two sessions (morning and afternoon session) of dynamic leg press action including knee extension and plantar flexion daily for the bed rest period: (1) three sets of 10 repetitions at 90% of maximum load and (2) 40% of maximum load to exhaustion. The PCSAs of the knee extensor (KE), knee flexor (KF), plantar flexor (PF), and dorsiflexor muscle groups were estimated using serial axial magnetic resonance (MR) images of the right-thigh and leg. After the bed rest period, the BR-Tr showed a significant increase in the PCSA of the KE. Although PCSA of the KF in two groups significantly decreased after bed rest, percentage of change in PCSA of the biceps femoris (long head) and semitendinosus muscles in the BR-Tr, which occupied approximately 70% of the KF, was significantly higher than those in the BR-Cont. Both the BR-Tr and BR-Cont groups showed significant decreases in the PCSA of PF with similar magnitude of 11.6% (P < 0.001) and 11.9% (P < 0.001), respectively. These results suggest that dynamic leg press training during bed rest can prevent deteriorating of the KE and a part of KF, but not the calf muscles.     

Effects of a short-term whole body vibration intervention on physical fitness in elderly people

We aimed to clarify whether a short-term whole body vibration (WBV) training has a beneficial effect on physical fitness in elderly people. Forty-nine non-institutionalized elderly (75.0 ± 4.7 years) participated in the study. Twenty-four of them trained on a vibration platform for 11 weeks. Physical fitness included balance, lower- and upper-body strength and flexibility, agility, walking speed and endurance. In the WBV group most of the physical tests improved through the intervention (all P < 0.01) while in the control group only an increment was detected in lower-body strength (P < 0.05). In conclusion, a short-term WBV training is beneficial for physical fitness among elderly people.     

Effects of prolonged bed rest on cardiovascular oxygen transport during submaximal exercise in humans

The hypothesis was tested that prolonged bed rest impairs O₂ transport during exercise, which implies a lowering of cardiac output Q˙ _c and O₂ delivery (_aO₂). The following parameters were determined in five males at rest and at the steady-state of the 100-W exercise before (B) and after (A) 42-day bed rest with head-down tilt at ?6°: O₂ consumption (V˙O₂), by a standard open-circuit method; Q˙ _c, by the pressure pulse contour method, heart rate (?f _c), stroke volume (Q _h), arterial O₂ saturation, blood haemoglobin concentration ([Hb]), arterial O₂ concentration (C _aO₂), and Q˙ _aO₂. The V˙O₂ was the same in A and in B, as was the resting f _c. The f _c at 100?W was higher in A than in B (+17.5%). The Q _h was markedly reduced (?27.7% and ?22.2% at rest and 100?W, respectively). The Q˙ _c was lower in A than in B [?27.6% and ?7.8% (NS) at rest and 100?W, respectively]. The C _aO₂ was lower in A than in B because of the reduction in [Hb]. Thus also Q˙ _aO₂ was lower in A than in B (?32.0% and ?11.9% at rest and at 100?W, respectively). The present results would suggest a down-regulation of the O₂ transport system after bed rest.     

Effects of age and inactivity due to prolonged bed rest on atrophy of trunk muscles

This study investigated the effects of age and inactivity due to being chronically bedridden on atrophy of trunk muscles. The subjects comprised 33 young women (young group) and 41 elderly women who resided in nursing homes or chronic care institutions. The elderly subjects were divided into two groups: independent elderly group who were able to perform activities of daily living involving walking independently (n = 28) and dependent elderly group who were chronically bedridden (n = 13). The thickness of the following six trunk muscles was measured by B-mode ultrasound: the rectus abdominis, external oblique, internal oblique, transversus abdominis, thoracic erector spinae (longissimus) and lumbar multifidus muscles. All muscles except for the transversus abdominis and lumbar multifidus muscles were significantly thinner in the independent elderly group compared with those in the young group. The thicknesses of all muscles in the dependent elderly group was significantly smaller than that in the young group, whereas there were no differences between the dependent elderly and independent elderly groups in the muscle thicknesses of the rectus abdominis and internal oblique muscles. In conclusion, our results suggest that: (1) age-related atrophy compared with young women was less in the deep antigravity trunk muscles than the superficial muscles in the independent elderly women; (2) atrophy associated with chronic bed rest was more marked in the antigravity muscles, such as the back and transversus abdominis.     

Effects of vibration and resistance training on neuromuscular and hormonal measures

The aim was to study whether whole body vibration (WBV) combined with conventional resistance training (CRT) induces a higher increase in neuromuscular and hormonal measures compared with CRT or WBV, respectively. Twenty-eight young men were randomized in three groups; squat only (S), combination of WBV and squat (S+V) and WBV only (V). S+V performed six sets with eight repetitions with corresponding eight repetition maximum (RM) loads on the vibrating platform, whereas S and V performed the same protocol without WBV and resistance, respectively. Maximal isometric voluntary contraction (MVC) with electromyography (EMG) measurements during leg press, counter movement jump (CMJ) measures (mechanical performance) including jump height, mean power (P _mean), peak power (P _peak) and velocity at P _peak (V _ppeak) and acute hormonal responses to training sessions were measured before and after a 9-week training period. ANOVA showed no significant changes between the three groups after training in any neuromuscular variable measured [except P _mean, S higher than V (P<0.05)]. However, applying t tests within each group revealed that MVC increased in S and S+V after training (P<0.05). Jump height, P _mean and P _peak increased only in S, concomitantly with increased V _ppeak in all groups (P<0.05). Testosterone increased during training sessions in S and S+V (P<0.05). Growth hormone (GH) increased in all groups but S+V showed higher responses than S and V (P<0.05). Cortisol increased only in S+V (P<0.05). We conclude that combined WBV and CRT did not additionally increase MVC and mechanical performance compared with CRT alone. Furthermore, WBV alone did not increase MVC and mechanical performance in spite of increased GH.     

Effects of short-term training on physiologic properties of human motor units.

The human neuromuscular system possesses a remarkable ability to adapt to any change in the demands placed upon it. Adaptation to training or disuse is reflected in the activation patterns and physiologic properties of the motor unit (MU) pool in a given muscle group. This review summarizes the studies that have examined such adaptation at the level of the single MU. Disuse, as revealed by electrophysiologic studies, results in impaired MU recruitment and smaller twitch tensions in low and high threshold MUs. Alternatively, shortterm training improves MU recruitment and generally results in larger MU twitch tensions. A method has been developed to physiologically characterize and longitudinally follow single thenar MUs. Studies utilizing these methods have demonstrated that MUs differing in their baseline physiologic characteristics respond very differently to identical short-term training programs. These observations at the single MU level provide insight into training adaptations in whole muscles and muscle groups.     

Effects of short-term physical training on the liver IGF-I in diabetic rats

To investigate the influence of short-term physical training on IGF-I concentrations in diabetic rats, male wistar rats were distributed into four groups: sedentary control, trained control, sedentary diabetic and trained diabetic. Diabetes was induced by Alloxan (32 mg/kg b.w.) and training protocol consisted of swimming 1 h/day, 5 days/week, during 4 weeks, supporting 5% b.w. At the end of this period, rats were sacrificed and blood was collected for determinations of serum glucose, insulin, albumin, IGF-I and hematocrit. Liver samples were used to determine glycogen, protein, DNA and IGF-I concentrations. Diabetes reduced insulin and IGF-I concentrations in blood and liver protein, ratio protein/DNA and IGF-I concentrations in liver and increased glycemia. Physical training reduced serum glucose and recovered hepatic glycogen stores in diabetic rats and reduced serum and liver IGF-I concentrations. In conclusion, short-term physical training improved the metabolic conditions of diabetic rats, despite of impairing liver and blood IGF-I concentrations.     

Effects of short-term physical training on the liver IGF-I in diabetic rats

To investigate the influence of short-term physical training on IGF-I concentrations in diabetic rats, male wistar rats were distributed into four groups: sedentary control, trained control, sedentary diabetic and trained diabetic. Diabetes was induced by Alloxan (32 mg/kg b.w.) and training protocol consisted of swimming 1 h/day, 5 days/week, during 4 weeks, supporting 5% b.w. At the end of this period, rats were sacrificed and blood was collected for determinations of serum glucose, insulin, albumin, IGF-I and hematocrit. Liver samples were used to determine glycogen, protein, DNA and IGF-I concentrations. Diabetes reduced insulin and IGF-I concentrations in blood and liver protein, ratio protein/DNA and IGF-I concentrations in liver and increased glycemia. Physical training reduced serum glucose and recovered hepatic glycogen stores in diabetic rats and reduced serum and liver IGF-I concentrations. In conclusion, short-term physical training improved the metabolic conditions of diabetic rats, despite of impairing liver and blood IGF-I concentrations.     

Effects of short-term endurance exercise training on vascular function in young males

We investigated effects of 6 days of endurance exercise training [cycling at 65% of peak oxygen consumption (VO_2peak) for 2 h a day on six consecutive days] on vascular function in young males. Measures of VO_2peak, arterial stiffness, calf vascular conductance and heart rate variability were obtained pre- and post-training. Indices of arterial stiffness were obtained by applanation tonometry to determine aortic augmentation index normalized to a heart rate of 75 bpm (AI _x @75 bpm), and central and peripheral pulse wave velocity (CPWV, PPWV). Resting and maximal calf vascular conductances were calculated from concurrent measures of blood pressure and calf blood flow using venous occlusion strain-gauge plethysmography. Time and frequency domain measures of heart rate variability were obtained from recording R–R intervals during supine and standing conditions. Both CPWV (5.9 ± 0.8 vs. 5.4 ± 0.8 m/s) and PPWV (9.7 ± 0.8 vs. 8.9 ± 1.3 m/s) were reduced following the training program. No significant changes were observed in AI _x @75 bpm, vascular conductance, heart rate variability or VO_2peak. These data indicate that changes in arterial stiffness independent of changes in heart rate variability or vascular conductance can be achieved in healthy young males following only 6 days of intense endurance exercise.     

Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters

Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes. Twenty-four physically and mentally healthy male volunteers (20–45 years) performed resistive vibration exercise (n=7), resistance exercise without vibration (n=8) or no exercise (n=9) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma. General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD⁺ subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S. We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters. In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise.