The effects of downhill and uphill exercise training on osteogenesis-related factors in ovariectomy-induced bone loss

The Effect of Moderate-Intensity Treadmill Exercise on Bone Mass and the Transcription of Peripheral Blood Mononuclear Cells in Ovariectomized Rats

Objective: Using RNA-sequencing technology to screen the effect of moderate-intensity treadmill exercise on the sensitive genes that affect bone mass in the peripheral blood mononuclear cells (PBMCs) of ovariectomized (OVX) rats.

Methods: Three-month-old female Sprague-Dawley rats of Specific Pathogen Free (SPF) grade were randomly divided into the sham operation (SHAM) group, OVX group, and OVX combined exercise (OVX + EX) group. The OVX + EX group performed moderate-intensity treadmill exercise for 17 weeks. Then, the body composition and bone mineral density (BMD) were measured, and the bone microstructure of the femur was observed. PBMCs were collected from the abdominal aorta, and the differential genes were analyzed by transcriptome sequencing to further screen sensitive genes.

Results: (1) In the OVX group, the body weight and body fat content were significantly higher than in the SHAM group while the muscle content and BMD were significantly lower than the SHAM group. (2) The trabecular bone parameters in the OVX group were significantly lower than in the SHAM group, and they were significantly higher in the OVX + EX group than in the OVX group. When compared with the SHAM group, the microstructure of the distal femur trabecular in the OVX group was severely damaged, suggest that the morphological structure of trabecular bone is severely damaged, the number of trabecular bones is reduced, and the thickness becomes thinner, which lead to the widening of the trabecular bone space and the appearance of osteoporosis. The number and continuity of the trabecular bones were higher in the OVX + EX group than in the OVX group. (3) A Venn diagram showed that there were 58 common differential genes, and the differential genes were mainly enriched in the PI3K-Akt signaling pathway. Five sensitive genes were screened including CCL2, Nos3, Tgfb3, ITGb4, and LpL. The expression of CCL2, Nos3, and Tgfb3 genes was closely related to multiple bone parameters.

Conclusion: Moderate-intensity treadmill exercise may improve the body composition and bone mass of the OVX group by upregulating CCL2 and other genes of the PBMC. The PBMCs in the peripheral blood can be a useful tool for monitoring the effect of exercise on bone health in postmenopausal osteoporosis.

Aerobic exercise attenuates the effects of ovariectomy and sedentarism on body composition and food intake in female rats

ABSTRACT Objective To evaluate the impact of low to moderate aerobic exercise and ovariectomy on body composition and food consumption in female rats. Methods Forty adult Wistar female rats (age: 23 weeks; body weight: 275.2±3.6g; mean±SEM) were divided into 4 groups (n=10): laparotomy-sedentary; laparotomy-exercised; ovariectomy-sedentary; and ovariectomy-exercised. The exercised groups were submitted to a treadmill running program (16m/min; 30min/day, 5 days/week), for 8 weeks. Body weight and food consumption were monitored during the experiment. Visceral fat and carcass water, protein, ash, fat and carbohydrate fractions were analyzed. Two-way ANOVA plus the Tukey’s post hoc test was used for comparisons and p<0.05 was considered significant. Results The ovariectomized (ovariectomy-sedentary+ovariectomy-exercised) and sedentary (laparotomy-sedentary+ovariectomy-sedentary) animals showed higher (p<0.05) weight gain, food consumption, food efficiency ratio and weight gain/body weight ratio than laparotomy animals (laparotomy-sedentary+laparotomy-exercised) and exercised (exercised laparotomy+exercised ovariectomy), respectively. The ovariectomized and sedentary animals showed higher (p<0.05) carcass weight, fat percentage and visceral fat than laparotomy and exercised rats, respectively. Conclusion Ovariectomy and physical inactivity increase obesogenic indicators, whereas regular aerobic exercise of low to moderate intensity attenuates these unfavorable effects in female rats.

Downhill Running: What Are The Effects and How Can We Adapt? A Narrative Review

Downhill running (DR) is a whole-body exercise model that is used to investigate the physiological consequences of eccentric muscle actions and/or exercise-induced muscle damage (EIMD). In a sporting context, DR sections can be part of running disciplines (off-road and road running) and can accentuate EIMD, leading to a reduction in performance. The purpose of this narrative review is to: (1) better inform on the acute and delayed physiological effects of DR; (2) identify and discuss, using a comprehensive approach, the DR characteristics that affect the physiological responses to DR and their potential interactions; (3) provide the current state of evidence on preventive and in-situ strategies to better adapt to DR. Key findings of this review show that DR may have an impact on exercise performance by altering muscle structure and function due to EIMD. In the majority of studies, EIMD are assessed through isometric maximal voluntary contraction, blood creatine kinase and delayed onset muscle soreness, with DR characteristics (slope, exercise duration, and running speed) acting as the main influencing factors. In previous studies, the median (25th percentile, Q1; 75th percentile, Q3) slope, exercise duration, and running speed were - 12% (- 15%; - 10%), 40 min (30 min; 45 min) and 11.3 km h-1 (9.8 km h-1; 12.9 km h-1), respectively. Regardless of DR characteristics, people the least accustomed to DR generally experienced the most EIMD. There is growing evidence to suggest that preventive strategies that consist of prior exposure to DR are the most effective to better tolerate DR. The effectiveness of in-situ strategies such as lower limb compression garments and specific footwear remains to be confirmed. Our review finally highlights important discrepancies between studies in the assessment of EIMD, DR protocols and populations, which prevent drawing firm conclusions on factors that most influence the response to DR, and adaptive strategies to DR.

Non-Powered automatic velocity-controlled wheeled walker improves gait and satisfaction in patients with hip fracture when walking downhill: A cross-over study

BACKGROUND

A standard four-wheeled walker is commonly used after surgery for hip fracture to aid ambulation. However, elderly patients experience some difficulties and are at risk for falls; therefore, attempts are being made to address these issues.

RESEARCH QUESTION

Does the non-powered automatic velocity-controlled (NPAVEC) wheeled walker improves the gait and satisfaction of patients with hip fractures when walking downhill using it?

METHODS

In this cross-over study, 21 participants performed three trials of walking downhill with two walkers (an NPAVEC wheeled walker and a standard four-wheeled walker) at a self-selected speed. We compared the lower limb surface electromyography data and self-reported satisfaction scores for both walkers.

RESULTS

Regarding the affected limb, the NPAVEC wheeled walker increased contraction in the vastus medialis (p = 0.003) and tibialis anterior (p = 0.014), and biceps femoris of the unaffected limb (p = 0.01). Additionally, participants reported greater satisfaction when using the NPAVEC wheeled walker (p < 0.001).

SIGNIFICANCE

An NPAVEC wheeled walker, compared to a four-wheeled walker, can assist patients recovering from hip fracture when walking downhill by improving the gait and increasing satisfaction.