Effectiveness of nutritional and exercise interventions to improve body composition and muscle strength or function in sarcopenic obese older adults: A systematic review

Abstract

Although sarcopenic obesity (SO) poses a major public health concern, a robust approach for the optimization of body composition and strength/function in SO has not yet been established. The purpose of this systematic review was to assess the effectiveness of nutritional (focusing on energy and protein modulation) and exercise interventions, either individually or combined, on body composition and strength/function in older adults with SO. MEDLINE, the Cochrane Central Register of Controlled Trials, CINAHL and SPORTDiscus were searched. Main inclusion criteria comprised sarcopenia as defined by the European Working Group on Sarcopenia in Older People (EWGSOP) and obesity defined as % body fat ≥40% (women) and ≥28% (men). Randomized controlled trials (RCTs), randomized controlled crossover trials and controlled clinical trials with older adults (mean age ≥65 years) following a nutritional regimen and/or an exercise training program were considered. Out of 109 full text articles identified, only two RCTs (61 participants) met the inclusion criteria. One study was a nutritional intervention adding 15 g protein·day⁻¹ (via cheese consumption) to the participants' habitual diet. The second study was a high-speed circuit resistance training intervention. Body composition did not change significantly in either of the studies. However, the exercise intervention improved significantly muscle strength and physical function. Although this review was limited by the small number of eligible studies, it provides evidence for the potential benefits of exercise and highlights the necessity for future research to develop effective interventions including dietary and exercise regimens to combat sarcopenic obesity.

Introduction

Sarcopenia is defined by the European Working Group on Sarcopenia in Older People (EWGSOP) as the age-related decline of muscle mass and strength or function [1]. Low strength and muscle mass are associated with poor functional status, physical impairments, frailty, increased risk of falls, loss of independence and higher mortality risk [1], [2]. It has been suggested that in older people, strength is a stronger predictor of functional impairment and mortality rates than absolute changes in muscle mass or lean mass alone [3], [4], [5], [6]. Secondary to functional impairments, muscle atrophy may also contribute to insulin resistance as muscle tissue plays the main role in glucose uptake and utilization [7]. According to a recent systematic review, the prevalence of sarcopenia may vary from 1% to 29% in community-dwellers and 14% to 33% in long-term care populations [8].

Another condition that can promote poor health is obesity, which is defined as ‘abnormal or excess body fat accumulation’ [9], and is a growing concern due to its progressively rising prevalence rates in older populations [10]. In 2010, 35% and 28% of adults 65 years of age and older were reported to be obese in the US and the UK, respectively [11], [12]. Similar to sarcopenia, obesity can increase the risk of falls and mobility limitations in older age [13], [14], and when used in conjunction with indices of body composition and fat distribution (waist circumference or waist to hip ratio) it may be associated with adverse health effects, such as cardiovascular disease, metabolic syndrome, diabetes mellitus and several cancers [15]. Furthermore, adipose tissue can infiltrate the muscle tissue [16] and mediate an inflammatory response [17], which can result in muscle atrophy, lower muscle quality and strength, and mobility losses [16], [18], [19].

The relationship between sarcopenia and obesity is complex, with the development/progression of one condition being closely connected to the other (Fig. 1). The condition where sarcopenia and obesity occur together has been termed sarcopenic obesity (SO) [20]. It has been suggested that SO can predispose older individuals to more physical disabilities, gait and balance abnormalities, and an increased risk of falls compared with either of the two conditions alone [21]. Individuals with SO are exposed to ~2.5 times higher risk of reporting Instrumental Activities of Daily Living (IADL) disabilities compared with adults without obesity but with sarcopenia, or adults with obesity but without sarcopenia [22]. This negative synergistic effect of sarcopenia and obesity is in accordance with the findings from the EPIDOS (EPIDemiologie de l'OSteoporose) study, which reported that among a cohort of 1308 women divided in four groups: (1) without sarcopenia or obesity (2) with obesity but not sarcopenia (3) with sarcopenia but not obesity, and (4) with SO; the latter was the poorest in terms of performing physical activities that required strength [23]. According to a meta-analysis of 12 prospective cohort studies with a total number of 35 287 participants, the adults with SO had a 24% higher risk of all-cause mortality compared with their healthy counterparts [24].

Although SO has gained significant attention from the scientific community in recent years, and a plethora of existing definitions and cut-offs for sarcopenia and obesity exist, there is no universally accepted definition for SO [1], [25], [26]. Depending on the definition criteria and cut-offs used, the prevalence rates of SO can vary up to 26-fold, which makes detection and management of the condition challenging for healthcare practitioners [27]. Moreover, there are operational challenges around the management of SO. While exercise training can be beneficial for both obesity and sarcopenia, the dietary management of obesity may require energy restriction, while management of sarcopenia requires an increased intake of macronutrients, especially protein [28].

This has resulted in a growing body of evidence highlighting potentially beneficial nutritional and exercise strategies, aiming to reverse or attenuate the negative effects of aging on body composition and physical function [29], [30], [31]. Particular focus has been placed on protein intake, energy modulation and resistance exercise [32], [33]. With regard to protein intake, there seems to be a consensus for the benefits of increased protein intake, ranging from 1.0 g kg bw⁻¹·day⁻¹ to 1.5 g·kg bw⁻¹·day⁻¹, with the higher values appropriate for those older adults with chronic conditions, sarcopenia and malnutrition, or when combined with resistance exercise [28], [34], [35].

However, there are relatively few intervention studies utilizing exercise training and/or nutritional regimens for older adults with SO [26], [36]. It appears that most intervention trials have aimed to attenuate muscle loss at an early stage rather than try to ‘reverse’ an established condition related to advanced aging such as sarcopenia or SO, which would be far more challenging [37]. Furthermore, to the best of our knowledge, there has been no systematic review to date assessing the effectiveness of nutritional and exercise strategies, alone or combined, to improve body composition and strength/function indices in older individuals with SO. Therefore, the purpose of this systematic review was to assess the evidence for the use of diets modulating energy and protein (or amino acids) content, exercise training regimens, or diet and exercise training combined, in older adults with SO.

The focus of this systematic review was to determine the effectiveness of protein or energy-modulating regimens, with or without exercise training on body composition and function in adults, 65 years of age and older with SO. In particular, our aims were to (1) determine changes in absolute muscle mass, total appendicular skeletal muscle (TASM), skeletal muscle index (SMI), fat mass, % body fat, body weight and body mass index (BMI), (2) assess changes in muscle strength and/or physical function (including muscle strength, power, gait speed and balance), and (3) evaluate the effect of these interventions on quality of life, metabolic profile, activities of daily living, adverse effects of supplementation or food choices, compliance rates, and changes in habitual dietary intake during or after the interventions.