Effects of Tai-Chi Chuan Practice on Patterns and Stability of Lower Limb Inter-Joint Coordination During Obstructed Gait in the Elderly

Losing balance or tripping during obstacle-crossing is one of the most frequent causes of falls in the elderly. As a low speed, low impact exercise, Tai Chi Chuan (TCC) can be promising in helping the elderly develop strategies for improved balance, inter-joint coordination, and end-point control during obstacle-crossing. This study investigates the effects of TCC training on the patterns and variability of the lower-limb inter-joint coordination during obstacle-crossing in the elderly. Fifteen older TCC practitioners and 15 healthy controls crossed obstacles of three different heights, while sagittal angles (x) and angular velocities (x′) of the hips, knees and ankles were measured and their phase angles obtained. The continuous relative phases (CRP) of the hip-knee and knee-ankle coordination were also calculated. The standard deviations of the CRP curve points were averaged to obtain deviation phase (DP) values for the stance and swing phases. The TCC group was found to cross obstacles with increased leading and trailing toe-clearances with unaltered CRP values when the swing toe was above the obstacle. Long-term TCC training altered the patterns and magnitudes of the CRPs primarily over double-limb support and significantly reduced the variabilities of leading knee-ankle and trailing hip-knee and knee-ankle CRP curves over the crossing cycle, regardless of obstacle height. The current results suggest that long-term TCC practice was helpful for a crossing strategy with significantly increased foot-obstacle clearances and reduced variability of the way the motions of the lower limb joints are coordinated during obstacle-crossing. These benefits may be explained by the long-lasting effects of continuous practice of the slow movement patterns emphasizing between-limb transfer of body weight in TCC.

The Efficacy of Brief School-Based Exercise Programs in Improving Pubertal Bone Mass and Physical Fitness: A Randomized Controlled Trial

Purpose: To examine the effects of three types of school-based exercises on bone health and physical fitness function in Chinese boys and girls. Methods: One hundred and seventy-four Chinese boys and girls were randomly assigned into four groups: (1) sham exercise (ShEx); (2) high-impact exercise (HiEx); (3) high-impact exercise with various directions (HiExVi); and (4) high-intensity interval exercise (HiInEx). Speed of sound (SOS) and physical fitness parameters were determined before and after six-month intervention. Results: At the end of six-month intervention, participants in all groups show an increment of SOS compared with the baseline (p < 0.05), and the changes were higher in HiEx (mean: 38.878 m/s, 95% CI: 32.885~44.872, p = 0.001) and HiExVi groups (49.317 m/s, 42.737~55.897, p < 0.001) compared with ShEx group (20.049 m/s, 13.751~26.346). Six-month exercise training generated a reduction of percent of body fat (PBF) and waist–hip ratio (WHR) (p < 0.05). The decrease of PBF was greater in HiExVi (−1.222%, −1.820~−0.624, p = 0.012) and HiInEx groups (−1.395%, −1.809~−0.982, p = 0.003), whereas the reduction of WHR was larger in HiEx (−0.026, −0.039~−0.014, p = 0.009), HiExVi (−0.024, −0.036~−0.012, p = 0.021), and HiInEx groups (−0.035, −0.046~−0.024, p < 0.001) compared with ShEx group. Balance function (BLF), vital capacity (VC), standing long jump (SLJ), and sit up (SU) increased in all intervention groups (p < 0.05). The BLF increased in HiEx (6.332 s, 4.136~8.528, p = 0.001), HiExVi (10.489 s, 8.934~12.045, p < 0.001), and HiInEx groups (9.103 s, 7.430~10.776, p < 0.001) showed a greater change than that of ShEx group (1.727 s, 0.684 ~2.770). The increment of VC (273.049 mL, 199.510~346.587, p < 0.001) and SU (2.537 times/min, 0.639~4.435, p = 0.017) was higher in HiInEx group, whereas the accrual in SLJ was larger in HiExVi (7.488 cm, 4.936~10.040, p = 0.007) compared with ShEx group (58.902 mL, 7.990 ~109.814; −0.463 times/min, −2.003~1.077; 1.488 cm, −0.654 ~3.630). Conclusion: The brief school-based exercises were effective in improving schoolchildren’s health, but they showed different effects, with HiEx mostly improving bone health, HiInEx largely benefiting physical fitness function, and HiExVi enhancing both bone and physical fitness.

Comparative effectiveness of different exercises on bone mineral density in postmenopausal women: a systematic review and network meta-analysis of randomized controlled trials

Objective: To compare and rank different exercise interventions on bone mineral density (BMD) in postmenopausal women. Data Sources and Study Selection: MEDLINE, EMBASE, CINAHL, AMED, the Cochrane Central Register of Controlled Trials (CENTRAL), Scopus and Web of Science were searched from database inception to January 2021 of randomized controlled studies investigating the effect of exercise more than six months on BMD in postmenopausal women. Data Extraction and Synthesis: Data at baseline and post intervention (or the change from baseline) were extracted. A Bayesian random-effects network meta-analysis was performed. Main Outcomes and Measures: The primary outcome was the change of BMD (at lumbar spine, femoral neck, and total hip) from baseline values. Effect size measures were mean differences with 95% credible intervals (CrIs). Results: We identified 3324 citations and included 66 studies with a total number of 4336 participants. Associated with BMD at lumbar spine (LS) improve were found for multicomponent exercise, resistance training, mind body exercise, lower impact exercise, high impact exercise, and whole body vibration. With regard to femoral neck (FN), only multicomponent exercise, whole body vibration, and mind body exercise were effective. As for total hip (TH), only multicomponent exercise, resistance training, and flexibility exercise were found to be beneficial. Moreover, No matter the age of postmenopausal women, and the duration of intervention (range between 6 to 18 months), some certain kinds of exercise could be performed to improve BMD at LS and FN. Conclusions and Relevance: This NMA confirms that exercise therapy has clear benefits on bone mineral density in postmenopausal women. It also shows that the magnitude of effect varies depending on the outcome of interest, the age of participants, and the duration of intervention. Clinicians might consult the ranking of the exercise intervention presented in this study, when designating an optimal, individualized exercise prescription to improve BMD.

Effects of Low Energy Availability on Bone Health in Endurance Athletes and High-Impact Exercise as A Potential Countermeasure: A Narrative Review

Endurance athletes expend large amounts of energy in prolonged high-intensity exercise and, due to the weight-sensitive nature of most endurance sports, often practice periods of dietary restriction. The Female Athlete Triad and Relative Energy Deficiency in Sport models consider endurance athletes at high-risk for suffering from low energy availability and associated health complications, including an increased chance of bone stress injury. Several studies have examined the effects of low energy availability on various parameters of bone structure and markers of bone (re)modelling; however, there are differences in findings and research methods and critical summaries are lacking. It is difficult for athletes to reduce energy expenditure or increase energy intake (to restore energy availability) in an environment where performance is a priority. Development of an alternative tool to help protect bone health would be beneficial. High-impact exercise can be highly osteogenic and energy efficient; however, at present, it is rarely utilized to promote bone health in endurance athletes. Therefore, with a view to reducing the prevalence of bone stress injury, the objectives of this review are to evaluate the effects of low energy availability on bone health in endurance athletes and explore whether a high-impact exercise intervention may help to prevent those effects from occurring.

Osteoclasts and Microgravity

Astronauts are at risk of losing 1.0 to 1.5% of their bone mass for every month they spend in space despite their adherence to high impact exercise training programs and dietary regimens designed to preserve their musculoskeletal system. This loss is the result of microgravity-related impairment of osteocyte and osteoblast function and the consequent upregulation of osteoclast-mediated bone resorption. This review describes the ontogeny of osteoclast hematopoietic stem cells, the contributions of macrophage colony stimulating factor, activator of NFkB and the calcineurin pathways make in osteoclast differentiation, and provides details of bone formation, the osteoclast cytoskeleton, the immune regulation of osteoclasts, and osteoclast mechanotransduction on Earth, in the microgravity of space, and in conditions of simulated microgravity. The article discusses the need to better understand how osteoclasts are able to function in zero gravity and reviews current and prospective therapies that may be used to treat osteoclast-mediated bone disease.