A Novel Low-Impact Resistance Exercise Program Increases Strength and Balance in Females Irrespective of Menopause Status

Abstract

Introduction: The reduction in sex hormone production across the menopause transition is thought to accelerate age-related decline in muscle mass, strength, and stability, increasing the risk of falls and fractures. We aimed to investigate whether a novel low-impact resistance exercise program could improve strength, balance, and body composition and whether any improvement was affected by menopause status.

Methods: Seventy healthy, moderately active pre- (PRE; 46.7 ± (SD) 3.2 yr), peri- (PERI; 52.3 ± 2.2 yr), or post- (POST; 57.0 ± 2.5 yr) menopausal females, not taking hormone replacement therapy (HRT), were randomized to continue habitual physical activity (CON; n = 25) or complete a supervised resistance exercise program 4 d·wk -1 for 12 wk (EXC; n = 45). Strength at the hip and shoulder (isokinetic dynamometer), dynamic balance (Y-balance), flexibility (sit-and-reach and back-scratch), muscle thickness (rectus femoris, vastus intermedius (VI), and medial deltoid), and lean and % body fat (dual-energy x-ray absorptiometry) were measured before and after training.

Results: Hip abduction and flexion peak torque (19% ± 48% and 20% ± 17%, respectively; P < 0.05), posterolateral and posteromedial balance (12% ± 15% and 13% ± 15%, respectively; P < 0.001), flexibility (21% ± 36%, P < 0.001), VI thickness (12% ± 19%, P = 0.032), and lean mass (2% ± 2%, P = 0.007) all increased over 12 wk in EXC, but not CON, with no difference in response between PRE, PERI, and POST. The changes in shoulder strength and body mass over 12 wk were not different between CON and EXC.

Conclusions: This is the first study to demonstrate that the decline in sex hormones and an increase in age across the menopause transition do not affect the ability of lower limb (hip) strength and balance to adapt to a low-impact resistance exercise training program in females not taking HRT.

Trial registration: ClinicalTrials.gov NCT05397418.

FIGURE 1

Consort diagram of study participant recruitment and allocation between 12 wk of supervised low-impact resistance exercise intervention (EXC) and habitual physical activity (CON) groups.

FIGURE 2

Graphical representation of the experimental protocol. Intervention of 12-wk supervised low-impact resistance exercise performed four times per week in the exercise group or habitual physical activity in control group. Strength of hip and shoulder abduction and flexion peak torque, balance, and flexibility were familiarized <2 wk before baseline (WK0) data collection. Strength, balance, and flexibility, as well as body composition measures of weight and waist, muscle thickness via ultrasound, and lean mass and % body fat from DXA, were collected at WK0 then at weeks 4 (WK4), 8 (WK8), and 12 (WK12). Blood samples collected for total cholesterol, total triglycerides, and HbA_1c analysis as well as questionnaires for quality of life (SF-36), sleep quality (PSQI), and enjoyment of exercise were collected at WK0 and WK12. Accelerometers recorded 7 d of physical activity during WK0 and WK12. *indicates measurement in the exercise group only at time point.

FIGURE 3

Low-impact resistance exercises utilizing resistance bands at the hip (A), arms (B, C), and ankle (C, D); hand weights (E, F, I); internal and external rotation of the hips (G, H); and challenges to postural stability (F, H, I).

FIGURE 4

Hip abduction (A), hip flexion (B), shoulder abduction (C), and shoulder flexion (D) peak torque before (0) and after 12 wk (12) of habitual physical activity (CON, n = 25) or a supervised low-impact resistance training program (EXC, n = 45). Data were analyzed with repeated-measures ANOVA between EXC and CON intervention groups (COMBINED) and within healthy pre- (PRE), peri- (PERI), and post- (POST) menopausal females. Data were analyzed with repeated-measures ANOVA. Values are mean ± SD. * represents a significant difference from 0, P < 0.05; ** represents a significant difference from 0, P < 0.001.

FIGURE 5

Anterior (A), posterolateral (B), posteromedial (C), and sit and reach (D) reach score (cm) before (0) and after 12 wk of habitual physical activity (CON, n = 25) or a supervised low-impact resistance training program (EXC, n = 45). Data were analyzed with repeated-measures ANOVA between EXC and CON intervention groups (COMBINED) and within healthy pre- (PRE), peri- (PERI), and post- (POST) menopausal females. Values are mean ± SD. * represents a significant difference from 0, P < 0.05; # represents a significant difference within the intervention group between the menopause groups, P < 0.05.