Effectiveness of nutritional countermeasures in microgravity and its ground-based analogues to ameliorate musculoskeletal and cardiopulmonary deconditioning-A Systematic Review.

A systematic review was performed to evaluate the effectiveness of nutrition as a standalone countermeasure to ameliorate the physiological adaptations of the musculoskeletal and cardiopulmonary systems associated with prolonged exposure to microgravity. A search strategy was developed to find all astronaut or human space flight bed rest simulation studies that compared individual nutritional countermeasures with non-intervention control groups. This systematic review followed the guidelines of the Cochrane Handbook for Systematic Reviews and tools created by the Aerospace Medicine Systematic Review Group for data extraction, quality assessment of studies and effect size. To ensure adequate reporting this systematic review followed the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analyses. A structured search was performed to screen for relevant articles. The initial search yielded 4031 studies of which 10 studies were eligible for final inclusion. Overall, the effect of nutritional countermeasure interventions on the investigated outcomes revealed that only one outcome was in favor of the intervention group, whereas six outcomes were in favor of the control group, and 43 outcomes showed no meaningful effect of nutritional countermeasure interventions at all. The main findings of this study were: (1) the heterogeneity of reported outcomes across studies, (2) the inconsistency of the methodology of the included studies (3) an absence of meaningful effects of standalone nutritional countermeasure interventions on musculoskeletal and cardiovascular outcomes, with a tendency towards detrimental effects on specific muscle outcomes associated with power in the lower extremities. This systematic review highlights the limited amount of studies investigating the effect of nutrition as a standalone countermeasure on operationally relevant outcome parameters. Therefore, based on the data available from the included studies in this systematic review, it cannot be expected that nutrition alone will be effective in maintaining musculoskeletal and cardiopulmonary integrity during space flight and bed rest.

Role of Oral Nutritional Supplements Enriched with ß-Hydroxy-ß-Methylbutyrate in Maintaining Muscle Function and Improving Clinical Outcomes in Various Clinical Settings.

Aging and disease-related malnutrition are well associated with loss of muscle mass and function. Muscle mass loss may lead to increased health complications and associated increase in health care costs, especially in hospitalized individuals. High protein oral nutritional supplements enriched with ß-hydroxy-ß-methylbutyrate (HP-ONS+HMB) have been suggested to provide benefits such as improving body composition, maintaining muscle mass and function and even decreasing mortality rates. The present review aimed to examine current evidence on the effect of HP-ONS+HMB on muscle-related clinical outcomes both in community and peri-hospitalization patients. Overall, current evidence suggests that therapeutic nutrition such as HP-ONS+HMB seems to be a promising tool to mitigate the decline in muscle mass and preserve muscle function, especially during hospital rehabilitation and recovery.

Vitamin D: Musculoskeletal health.

Perhaps the role of Vitamin D supplementation has been most exhaustively studied in calcium absorption, skeletal wellbeing, muscular potency, balance and risk of falling. Nonetheless, new data has emerged and the recent research on sarcopenia makes the topic increasingly interesting. Given the socioeconomic burden of the musculoskeletal consequences of hypovitaminosis D it is vital to keep abreast with the latest literature in the field. The recommended Vitamin D supplementation dose should suffice to increase the serum 25 hydroxyvitamin D level to 30 ng/mL (75 nmol/L) and this level should be optimally maintained with a maintenance dose, particularly for those diagnosed with osteoporosis.

Effects of Arachidonic Acid Supplementation on Acute Anabolic Signaling and Chronic Functional Performance and Body Composition Adaptations.

BACKGROUND: The primary purpose of this investigation was to examine the effects of arachidonic acid (ARA) supplementation on functional performance and body composition in trained males. In addition, we performed a secondary study looking at molecular responses of ARA supplementation following an acute exercise bout in rodents. METHODS: Thirty strength-trained males (age: 20.4 ± 2.1 yrs) were randomly divided into two groups: ARA or placebo (i.e. CTL). Then, both groups underwent an 8-week, 3-day per week, non-periodized training protocol. Quadriceps muscle thickness, whole-body composition scan (DEXA), muscle strength, and power were assessed at baseline and post-test. In the rodent model, male Wistar rats (~250 g, ~8 weeks old) were pre-fed with either ARA or water (CTL) for 8 days and were fed the final dose of ARA prior to being acutely strength trained via electrical stimulation on unilateral plantar flexions. A mixed muscle sample was removed from the exercised and non-exercised leg 3 hours post-exercise. RESULTS: Lean body mass (2.9%, p<0.0005), upper-body strength (8.7%, p<0.0001), and peak power (12.7%, p<0.0001) increased only in the ARA group. For the animal trial, GSK-ß (Ser9) phosphorylation (p<0.001) independent of exercise and AMPK phosphorylation after exercise (p-AMPK less in ARA, p = 0.041) were different in ARA-fed versus CTL rats. CONCLUSIONS: Our findings suggest that ARA supplementation can positively augment strength-training induced adaptations in resistance-trained males. However, chronic studies at the molecular level are required to further elucidate how ARA combined with strength training affect muscle adaptation.

Green tea extract attenuates muscle loss and improves muscle function during disuse, but fails to improve muscle recovery following unloading in aged rats.

In this study we tested the hypothesis that green tea extract (GTE) would improve muscle recovery after reloading following disuse. Aged (32 mo) Fischer 344 Brown Norway rats were randomly assigned to receive either 14 days of hindlimb suspension (HLS) or 14 days of HLS followed by normal ambulatory function for 14 days (recovery). Additional animals served as cage controls. The rats were given GTE (50 mg/kg body wt) or water (vehicle) by gavage 7 days before and throughout the experimental periods. Compared with vehicle treatment, GTE significantly attenuated the loss of hindlimb plantaris muscle mass (-24.8% vs. -10.7%, P < 0.05) and tetanic force (-43.7% vs. -25.9%, P <0.05) during HLS. Although GTE failed to further improve recovery of muscle function or mass compared with vehicle treatment, animals given green tea via gavage maintained the lower losses of muscle mass that were found during HLS (-25.2% vs. -16.0%, P < 0.05) and force (-45.7 vs. -34.4%, P < 0.05) after the reloading periods. In addition, compared with vehicle treatment, GTE attenuated muscle fiber cross-sectional area loss in both plantaris (-39.9% vs. -23.9%, P < 0.05) and soleus (-37.2% vs. -17.6%) muscles after HLS. This green tea-induced difference was not transient but was maintained over the reloading period for plantaris (-45.6% vs. -21.5%, P <0.05) and soleus muscle fiber cross-sectional area (-38.7% vs. -10.9%, P <0.05). GTE increased satellite cell proliferation and differentiation in plantaris and soleus muscles during recovery from HLS compared with vehicle-treated muscles and decreased oxidative stress and abundance of the Bcl-2-associated X protein (Bax), yet this did not further improve muscle recovery in reloaded muscles. These data suggest that muscle recovery following disuse in aging is complex. Although satellite cell proliferation and differentiation are critical for muscle repair to occur, green tea-induced changes in satellite cell number is by itself insufficient to improve muscle recovery following a period of atrophy in old rats.

A phase IIA randomized, placebo-controlled clinical trial to study the efficacy and safety of the selective androgen receptor modulator (SARM), MK-0773 in female participants with sarcopenia.

BACKGROUND: Sarcopenia, the age-related loss of muscle mass [defined as appendicular LBM/Height2 (aLBM/ht2) below peak value by>1SD], strength and function, is a major contributing factor to frailty in the elderly. MK-0773 is a selective androgen receptor modulator designed to improve muscle function while minimizing effects on other tissues. OBJECTIVES: The primary objective of this study was to demonstrate an improvement in muscle strength and lean body mass (LBM) in sarcopenic frail elderly women treated with MK-0773 relative to placebo. DESIGN: This was a randomized, double-blind, parallel-arm, placebo-controlled, multicenter, 6-month study. Participants were randomized in a 1:1 ratio to receive either MK-0773 50mg b.i.d. or placebo; all participants received Vitamin D and protein supplementation. SETTING: General community. PARTICIPANTS: 170 Women aged ≥65 with sarcopenia and moderate physical dysfunction. MEASUREMENTS: Dual energy X-ray absorptiometry, muscle strength and power, physical performance measures. RESULTS: Participants receiving MK-0773 showed a statistically significant increase in LBM from baseline at Month 6 vs. placebo (p<0.001). Participants receiving both MK-0773 and placebo showed a statistically significant increase in strength from baseline to Month 6, but the mean difference between the two groups was not significant (p=0.269). Both groups showed significant improvement from baseline at Month 6 in physical performance measures, but there were no statistically significant differences between participants receiving MK-0773 and placebo. A greater number of participants experienced elevated transaminases in the MK-0773 group vs. placebo, which resolved after discontinuation of study therapy. MK-0773 was generally well-tolerated with no evidence of androgenization. CONCLUSIONS: The MK-0773-induced increase in LBM did not translate to improvement in strength or function vs. placebo. The improvement of strength and physical function in the placebo group could be at least partly attributed to protein and vitamin D supplementation.

Do fat supplements increase physical performance?

Fish oil and conjugated linoleic acid (CLA) belong to a popular class of food supplements known as "fat supplements", which are claimed to reduce muscle glycogen breakdown, reduce body mass, as well as reduce muscle damage and inflammatory responses. Sport athletes consume fish oil and CLA mainly to increase lean body mass and reduce body fat. Recent evidence indicates that this kind of supplementation may have other side-effects and a new role has been identified in steroidogenensis. Preliminary findings demonstrate that fish oil and CLA may induce a physiological increase in testosterone synthesis. The aim of this review is to describe the effects of fish oil and CLA on physical performance (endurance and resistance exercise), and highlight the new results on the effects on testosterone biosynthesis. In view of these new data, we can hypothesize that fat supplements may improve the anabolic effect of exercise.

Effect of botulinum toxin injection on length and lengthening velocity of rectus femoris during gait in hemiparetic patients.

BACKGROUND: In hemiparetic patients, rectus femoris spasticity is one of the main causes of reduced knee flexion in swing phase, known as stiff knee gait. Botulinum toxin is often used to reduce rectus femoris spasticity and to increase knee flexion during swing phase. However, the mechanisms behind these improvements remain poorly understood. The aim of this study was (1) to quantify maximal rectus femoris length and lengthening velocity during gait in ten adult hemiparetic subjects with rectus femoris spasticity and stiff knee gait and to compare these parameters with those of ten healthy subjects and (2) to study the effect of botulinum toxin injection in the rectus femoris muscle on the same parameters. METHODS: 10 patients with stiff knee gait and rectus femoris spasticity underwent 3D gait analysis before and one month after botulinum toxin injection of the rectus femoris (200 U Botox, Allergan Inc., Markham, Ontario, CANADA). Rectus femoris length and lengthening velocity were quantified using a musculoskeletal model (SIMM, MusculoGraphics, Inc., Santa Rosa, California, USA). FINDINGS: Maximal length and lengthening velocity of the rectus femoris were significantly reduced on the paretic side. There was a significant increase in muscle length as well as lengthening velocity during gait following botulinum toxin injection. INTERPRETATION: This study showed that botulinum toxin injection in the spastic rectus femoris of hemiparetic patients improves muscle kinematics during gait. However maximal rectus femoris length did not reach normal values following injection, suggesting that other mechanisms are likely involved.

A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females.

CONTEXT: There has been a resurgence of vitamin D deficiency rickets throughout the developed world, with infants and adolescents being primarily affected. Adolescence is a crucial period for muscle and bone mineral accumulation. OBJECTIVE: The aim was to determine the effect of vitamin D supplementation on the adolescent musculoskeletal system. DESIGN AND SETTING: We conducted a community-based, double-blind, randomized controlled trial in a secondary school. PARTICIPANTS: Postmenarchal 12- to 14-yr-old females participated in the trial. Ninety-nine were screened, 73 were included in randomized controlled trial, and 69 completed the trial. There were no adverse events. INTERVENTION: Four doses of 150,000 IU vitamin D(2) (ergocalciferol) were given over 1 yr. MAIN OUTCOME MEASURES: Dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and jumping mechanography were used. RESULTS: At follow-up, 25-hydroxyvitamin D [25(OH)D] status was 56.0 ± 8.9 nmol/liter in the intervention group and 15.8 ± 6.6 nmol/liter in controls. There were no effects of supplementation on bone; however, for muscle function, efficiency of movement improved in the vitamin D-treated group. There was an interaction between baseline 25(OH)D concentration and response to vitamin D supplementation for muscle jump velocity. CONCLUSIONS: Despite improvements in 25(OH)D status, treatment with vitamin D(2) was not shown to increase mineral accretion, bone geometry or strength, muscle force, or power. There were greater increases in jump velocity in girls with the lowest baseline 25(OH)D concentrations. Lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required.

Administration of caffeic acid worsened bone mechanical properties in female rats.

Natural phenolic acids, commonly present in plants that are normally consumed in the diet, have been reported to exert antiresorptive and/or bone formation increasing activity. The aim of the present study was to investigate the effects of ferulic, caffeic, P-coumaric, and chlorogenic acids on the skeletal system of normal, mature female rats. The phenolic acids (10 mg/kg p. o. daily for 4 weeks) were administered to 3-month-old female Wistar Cmd:(WI)WU rats. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. Phenolic acids had differential effects on the rat skeletal system. Although none of them affected bone macrometric parameters, mass and mineralization, all of them increased the width of femoral trabeculae. Administration of caffeic acid worsened bone mechanical properties (decreasing ultimate load sustained by the femur in three-point bending test). In conclusion, high intake of caffeic acid may unfavorably affect the skeletal system.

[Preliminary study on protecting effect of two kinds of Chinese medical herbs on changes of three physiology systems in suspended rats].

Objective. To observe the protecting effect of two kinds of Chinese medical herbs on changes of blood circulation, muscle and skeletal systems in tail suspended rats. Method. Changes of blood circulation, muscle and skeletal systems in tail suspended rats (n=15), Chinese medical herb group 1 (n=15) and Chinese medical herb group 2 (n=15) after 30 d tail suspension were compared with those in control group rats (n=15). Result. Two kinds of Chinese medical herbs have obvious effect on improving the condition of blood circulation, and have some effects on improving the muscle and skeletal systems in tail suspended rats. Conclusion. Chinese medical herbs have a good prospect of being used in space flight, and further studies are needed.

Androgen supplementation in older women: too much hype, not enough data.

Androgen supplementation in women has received enormous attention in the scientific and lay communities. That it enhances some aspects of cognitive function, sexual function, muscle mass, strength, and sense of well-being is not in question. What is not known is whether physiological testosterone replacement can improve health-related outcome in older women without its virilizing side effects. Although it is assumed that the testosterone dose-response relationship is different in women than in men and that clinically relevant outcomes on the above-mentioned effects can be achieved at lower testosterone doses, these assumptions have not been tested rigorously. Androgen deficiency has no clear-cut definition. Clinical features may include impaired sexual function, low energy, depression, and a total testosterone level of less than 15 ng/dL, the lower end of the normal range. Measurement of free testosterone is ideal, because it provides a better estimate of the biologically relevant fraction. It is not widely used in clinical practice, because some methods of measuring free testosterone assay are hampered by methodological difficulties. In marked contrast to the abrupt decline in estrogen and progesterone production at menopause, serum testosterone is lower in older women than in menstruating women, with the decline becoming apparent a decade before menopause. This article reviews testosterone's effects on sexual function, cognitive function, muscle mass, body composition, and immune function in postmenopausal women.