The Chronic Effects of a Quantified Jump-Landing Program on Bone Health, Body Composition and Performance Parameters in Premenopausal Women

Research Article

J Fam Med. 2022; 9(1): 1287.

The Chronic Effects of a Quantified Jump-Landing Program on Bone Health, Body Composition and Performance Parameters in Premenopausal Women

Clissold TL1,2, Cronin JB2,3, De Souza MJ4 and Winwood PW1,2*

1Toi Ohomai Institute of Technology, Department of Sport and Fitness, Faculty of Health, Education and Environment, Tauranga, New Zealand

2AUT University, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, Auckland, New Zealand

3School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, Australia

4Department of Kinesiology, Pennsylvania State University, Pennsylvania, USA

*Corresponding author: Paul Winwood, Department of Sport and Fitness, Faculty of Health, Education and Environment, Toi Ohomai Institute of Technology, Private Bag 12001, Tauranga 3143, New Zealand

Received: December 14, 2021; Accepted: January 17, 2022; Published: January 24, 2022

Abstract

The primary purpose of this study was to determine the effects of a 12-month quantified jump-landing program at clinically relevant bone sites in premenopausal women. Secondary measures of interest included; lower body explosive power, muscle reactivity, balance performance parameters and body composition. A longitudinal controlled trial was implemented to determine the effect of utilizing previously quantified jumps and hops with specific cues provided for jump-landings. Participants; Fifty-seven women (age, 42.4 ± 5.50 y; body mass, 70.2 ± 11.5 kg; height, 165.4 ± 0.10 cm; body fat, 31.5 ± 6.20%) were assigned to a jump (JL) or control (CON) group. The JL performed periodized jumping-landing exercises up to five times per week for 12-months. Linear mixed model regression analysis was used to determine if differences existed between the JL and CON. Significant group main effects (P<0.01) in favour of the JL (↑0.41 - ↑3.72%) were observed for bone mineral density and bone mineral content at the femoral neck, total hip and lumbar spine. Significant group main effects (P<0.01) for cross-sectional area, cortical thickness and section modulus at the femoral narrow neck were also in favour of the JL (↑2.78 - ↑3.84%). For ground contact time, improvements in the JL over the CON between baseline and 12-months were apparent (↑21.9% vs. ↓8.86%) with significant group and time effects (P<0.01) being observed. A longitudinal quantified periodized jumplanding program performed 2-3 mins/day; 4-5 times a week is osteogenically effective in improving bone strength at clinically relevant lower body sites associated with osteoporosis in premenopausal women.

Keywords: Exercise; Osteoporosis; Fracture prevention; Biomechanics; DXA

Introduction

Osteoporosis has been described as a silent epidemic responsible for fractures in 50% of women and 20% of men worldwide [1,2]. In the United States approximately 52 million women and men have osteoporosis or osteopenia (low bone mass) and it is predicted to increase to more than 61 million by 2020 if additional efforts are not made to address this disease [3]. It is well accepted that women have less total bone mass than men and experience rapid bone loss during menopause. Generally women experience bone losses of approximately 1% per year after the fourth decade of life, however annual losses of 3 - 5% bone mineral density (BMD) can be experienced during early post-menopause [4]. The National Osteoporosis Foundation of America estimate up to 20% of BMD can be lost in the 5 - 7 years after menopause, with lifetime bone losses estimated to be 30 - 40% of peak bone mass [4,5].

The measurement of ground reaction forces (GRF’s), represented as body weight’s (BW’s) have been used to estimate the influence of loading on bone [6-9], and researchers have suggested that to achieve an adaptive bone response an exercise regime should satisfy the following criteria: a) be of sufficient magnitude and rate of strain; b) present its strain in a range of diverse and unusual distribution patterns; c) provide a limited number of loading cycles at each distribution; d) be of short duration; and e) provide adequate recovery periods. However, research has predominantly focused on “high risk” postmenopausal women and as a consequence exercise regimes for minimizing bone loss in adults are generic and lack specific recommendations for women before they experience accelerated bone losses during and post menopause [10,11].

Jumping and hopping exercises have been researched for their role in enhancing bone mass in young people and for minimizing age-related bone loss in females [6,12-17]. Exercises, with emphasis on the jump-landing, may be of special interest given their role in increasing peak bone mass in premenopausal women and minimizing age-related bone loss [13,18-20]. Authors of meta-analyses concluded [18,19] that jump-landing programs that; utilized brief jumping protocols (10-100 jumps/day, 3 - 7 days/week), are 4 - 18 months duration, and present loading magnitudes of between 2 - 6 BW, can result in significant gains in femoral neck BMD of 0.5 - 3% in premenopausal women during a time when normal bone loss is 0.5% - 1% per year [18,21].

Recently researchers investigated the vertical and resultant GRF’s associated with bilateral vertical jumps, countermovement and drop jumps combined with a reactive jump (defined as ‘jumping immediately after an initial jump-landing’) as a potential osteogenic stimuli for premenopausal women [22]. The authors reported peak vertical landing forces (4.6 - 5.5 BW) which were substantially higher (1.2 to 1.8 times greater) than the values previously reported for the same jump-landings performed by a similar populations [13,20,23]. The use of repeated jumps requires the participant to flex minimally upon landing and push off quickly thereafter, thus preventing a ‘soft’ landing and the absorption of impact energy by the leg musculature [24-26].

Recent exercise prescription guidelines for the prevention and management of osteoporosis have been published by Exercise and Sports Science Australia (ESSA), according to level of risk of fragility fracture [27]. Individuals classified as ‘low risk’ (T score < -1.0), are recommended to perform moderate to high-impact weight-bearing activities (50 jumps per session), defined as greater than two body weights (BW) (moderate impact), to greater than four body weights (high impact) of ground reaction forces, four to seven times each week. Although the position statement identifies the types of jumps to be performed, it lacks specific detail in terms of jump-landing technique, program design, and monitoring of the daily and weekly loading. Therefore a program to safely optimize the impact stimulus required to promote bone formation needs to provide specific cues for jump-landings and adhere to best practice musculoskeletal program design [28-31].

Although the effects of jumping exercises on bone health in premenopausal women have been documented by several research groups, many diverse protocols are used in exercise and BMD research, making it challenging to compare outcomes. In addition, the focus on jump-landing technique and utilizing a reactive jump component within a 12-month periodized training program has not been previously presented. Given the limitation identified, the primary outcome this study sought to determine was whether the jump group (JL) would achieve and exceed gains in bone mass, and improved aspects of bone geometry at the femoral narrow neck (cortical thickness, cross-sectional area, section modulus). We were also interested in secondary measures associated with the reduction of falls risk, including; lower body explosive power, muscle reactivity and body composition. Due to the scope of the study, several hypotheses were generated; i) Bone mineral density and bone mineral content will increase at the femoral neck, total hip and lumbar spine in the JL and age-predicted BMD losses (=1%) will occur in the control group (CON); ii) Bone geometry variables will increase at the femoral neck in the JL and decrease in the CON; iii) Improvements in functional performance parameters (i.e. lower body explosive power and muscle reactivity), will be observed in the JL only; and, iv) The JL will achieve improvements in body composition (i.e. increased fat free mass and decreased fat mass and body fat percentage), with no improvements in the CON.

Methods

A longitudinal controlled trial was implemented for a period of 12-months to determine the effects of a quantified jump-landing program on measurements of bone health in premenopausal women. Eighty premenopausal women (30 - 51 years) were assigned to either the JL or CON. Participants utilized an online registration form in which they could indicate a preference for treatment, control or either. Fifty percent (n = 40) chose either and were randomized into the JL or CON group. The remaining participants were allocated based on their ability to participate in the daily jump-landing program (in their own homes), and attend jump-landing group classes regularly. Such methodology was deemed necessary as previously published longitudinal exercise studies involving premenopausal women have reported high dropout rates 38% to 50% [23,32,33]. Studies with an insufficient sample size may not have sufficient statistical power to detect meaningful effects and may produce unreliable answers to important research questions [34]. The current study design sought to improve the adherence to the jump-landing training program [33] and to determine the true meaningful effect of the mechanical stimulus associated with the jump landings. Although it was not possible to blind the intervention providers due to their specific expertise in the field of this research, blinding was applied for the process of data entry and analysis.

Participants in the CON were asked to maintain their normal activity level and to attend 3-monthly testing sessions. No significant differences for any physiological measures were observed between the CON and JL group at baseline. All testing was performed at baseline, 3, 6, 9 and 12-month intervals in a Sports Science laboratory at a local Institute of Technology. All participants provided written informed consent after being briefed on the potential risks associated with this research. The methods and procedures used in this study were approved by the New Zealand Health and Disability Ethics Committees (17/NTB/155), and registered with the Australian New Zealand Clinical Trials Registry (ACTRN12617001145392p).

Participants

Eighty healthy premenopausal women (30 - 51 years), from the Bay of Plenty community, New Zealand (including; Toi Ohomai Institute of Technology and Sport Bay of Plenty), volunteered to participate in this study in response to intra and inter- institution advertisement. This sample size is comparable to other studies which have used a similar design and length of study [13,35,36]. A flow diagram depicting the recruitment and retention of participants during the study is presented in Figure 1. Of the eighty participants, eight did not meet the inclusion criteria due to regular participation in sport or exercise involving high impact activities (n = 8). A further fifteen women were removed from the study due to either; becoming pregnant (n = 4), sustaining an unrelated injury (n = 6), leaving the region (n = 3), or withdrawing for personal reasons (n = 2). The results from this study are based on the data obtained by the remaining 57 participants (Table 1).