Milk and resistance exercise intervention to improve muscle function in community-dwelling older adults at risk of sarcopenia (MIlkMAN): protocol for a pilot study

Frontiers in sarcopenia: Advancements in diagnostics, molecular mechanisms, and therapeutic strategies

The onset of sarcopenia is intimately linked with aging, posing significant implications not only for individual patient quality of life but also for the broader societal healthcare framework. Early and accurate identification of sarcopenia and a comprehensive understanding of its mechanistic underpinnings and therapeutic targets paramount to addressing this condition effectively. This review endeavors to present a cohesive overview of recent advancements in sarcopenia research and diagnosis. We initially delve into the contemporary diagnostic criteria, specifically referencing the European Working Group on Sarcopenia in Older People (EWGSOP) 2 and Asian Working Group on Sarcopenia (AWGS) 2019 benchmarks. Additionally, we elucidate comprehensive assessment techniques for muscle strength, quantity, and physical performance, highlighting tools such as grip strength, chair stand test, dual-energy X-ray Absorptiometry (DEXA), bioelectrical impedance analysis (BIA), gait speed, and short physical performance battery (SPPB), while also discussing their inherent advantages and limitations. Such diagnostic advancements pave the way for early identification and unequivocal diagnosis of sarcopenia. Proceeding further, we provide a deep-dive into sarcopenia's pathogenesis, offering a thorough examination of associated signaling pathways like the Myostatin, AMP-activated protein kinase (AMPK), insulin/IGF-1 Signaling (IIS), and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. Each pathway's role in sarcopenia mediation is detailed, underscoring potential therapeutic target avenues. From a mechanistic perspective, the review also underscores the pivotal role of mitochondrial dysfunction in sarcopenia, emphasizing elements such as mitochondrial oxidative overload, mitochondrial biogenesis, and mitophagy, and highlighting their therapeutic significance. At last, we capture recent strides made in sarcopenia treatment, ranging from nutritional and exercise interventions to potential pharmacological and supplementation strategies. In sum, this review meticulously synthesizes the latest scientific developments in sarcopenia, aiming to enhance diagnostic precision in clinical practice and provide comprehensive insights into refined mechanistic targets and innovative therapeutic interventions, ultimately contributing to optimized patient care and advancements in the field.

Non-pharmacological interventions for possible sarcopenia or sarcopenia in community-dwelling older adults: a scoping review protocol

INTRODUCTION

Early prevention of sarcopenia is a recommendation to reduce morbidity, mortality and improve quality of life. Several non-pharmacological interventions to reduce the risk of sarcopenia in community-dwelling older people have been proposed. Therefore, there is a need to identify the scope and differences of these interventions. This scoping review will summarise the nature and extent of the existing literature that describes and examines non-pharmacological interventions for community-dwelling older adults with possible sarcopenia or sarcopenia.

METHODS AND ANALYSIS

The seven-stage review methodology framework will be used. Searches will be conducted in the following databases: Embase, Medline, PsycINFO, CINAHL, All EBM Reviews, Web of Science, Scopus, CBM, CNKI, WANFANG and VIP. Grey literature will also be identified from Google scholar. Search dates will be restricted to January 2010 to December 2022, in English and Chinese language only. Screening will be focused on published research, including both quantitative and qualitative study designs, and prospectively registered trials. Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews will be followed when delineating the search decision process. Findings will be synthesised quantitatively and qualitatively as appropriate and classified using key conceptual categories. We will identify whether studies identified have been included in systematic reviews or meta-analyses, and research gaps and opportunities will be identified and summarised.

ETHICS AND DISSEMINATION

As this is a review, ethical approval will not be sought. The results will be published in peer-reviewed scientific journals and also disseminated in relevant disease support groups and conferences. The planned scoping review will help us identify the current status of research and gaps in the literature, so as to develop a future research agenda.

Effects of Icelandic yogurt consumption and resistance training in healthy untrained older males

Due to the important roles of resistance training and protein consumption in the prevention and treatment of sarcopenia, we assessed the efficacy of post-exercise Icelandic yogurt consumption on lean mass, strength and skeletal muscle regulatory factors in healthy untrained older males. Thirty healthy untrained older males (age = 68 ± 4 years) were randomly assigned to Icelandic yogurt (IR; n 15, 18 g of protein) or an iso-energetic placebo (PR; n 15, 0 g protein) immediately following resistance training (3×/week) for 8 weeks. Before and after training, lean mass, strength and skeletal muscle regulatory factors (insulin-like growth factor-1 (IGF-1), transforming growth factor-beta 1 (TGF-β1), growth differentiation factor 15 (GDF15), Activin A, myostatin (MST) and follistatin (FST)) were assessed. There were group × time interactions (P < 0·05) for body mass (IR: Δ 1, PR: Δ 0·7 kg), BMI (IR: Δ 0·3, PR: Δ 0·2 kg/m²), lean mass (IR: Δ 1·3, PR: Δ 0·6 kg), bench press (IR: Δ 4, PR: 2·3 kg), leg press (IR: Δ 4·2, PR: Δ 2·5 kg), IGF-1 (IR: Δ 0·5, Δ PR: 0·1 ng/ml), TGF-β (IR: Δ - 0·2, PR: Δ - 0·1 ng/ml), GDF15 (IR: Δ - 10·3, PR: Δ - 4·8 pg/ml), Activin A (IR: Δ - 9·8, PR: Δ - 2·9 pg/ml), MST (IR: Δ - 0·1, PR: Δ - 0·04 ng/ml) and FST (IR: Δ 0·09, PR: Δ 0·03 ng/ml), with Icelandic yogurt consumption resulting in greater changes compared with placebo. The addition of Icelandic yogurt consumption to a resistance training programme improved lean mass, strength and altered skeletal muscle regulatory factors in healthy untrained older males compared with placebo. Therefore, Icelandic yogurt as a nutrient-dense source and cost-effective supplement enhances muscular gains mediated by resistance training and consequently may be used as a strategy for the prevention of sarcopenia.

Interventions to Improve Body Composition, Upper and Lower Extremity Muscle Strength, and Balance Ability of Older Female Adults: An Intervention Study

The aim of the present study was to understand the effects of a moderate-intensity physical activity program on the changes observed in the body composition, upper and lower extremity muscle strength, as well as balance in elderly female adults in order to evaluate sarcopenia. In this study, 30 healthy elderly females were recruited and were randomly assigned to either the control group or the experimental group. The experimental group engaged in a moderate-intensity physical activity program twice a week for 8 weeks. Using a body composition analyzer, the senior fitness test, and handgrip strength and gait speed tests, all participants were tested in pre- and post-tests. The results of the study revealed changes in the overall body composition in the experimental group, with significant decreases in body mass index, body fat percentage, and body fat mass and substantial increases in the basal metabolic rate and skeletal muscle mass, while the upper and lower extremity muscle strength and balance ability also showed significant improvements. The moderate-intensity physical activity program also increased upper limb handgrip strength and lower limb gait speed, showing that the plan was able to effectively evaluate sarcopenia. The study concluded that using upper limb handgrip strength and lower limb walking speed to evaluate sarcopenia are useful diagnostic tools. Moderate-intensity physical activity is effective for improving muscle strength and reducing sarcopenia.

A review of the components of exercise prescription for sarcopenic older adults

PURPOSE

To synthesize the details of the exercises/exercise program prescribed for the improvement of muscle mass/muscle strength/physical performance among sarcopenic older adults.

METHODS

A systematic literature search was conducted in five electronic databases and the details of exercises such as single component or multicomponent exercise program, frequency/week, intensity, duration of the exercise program, type of exercises, progression, adverse events reported, outcome measures used, and whether technology or other educational aids were used to deliver the program were extracted.

RESULTS

A total of 10,045 records were identified and 27 records were included. Resistance exercises were included in all the studies, with the frequency ranging from 1 to 5/week, intensity ranging from 20 to 80% of 1 repetition maximum (RM), or 6-14 points on ratings of perceived exertion (RPE), and duration per session ranging from 20 to 75 min. The intensity of aerobic exercises ranged from 50 to 70% of heart rate max or a level of 7-17 in RPE with a duration ranging from 6 to 30 min per session for 2-5 days/week. For balance exercises, the intensity was mentioned as the level of effort 3 on a scale of 10, and the time duration per session ranged from 5 to 30 min for a frequency of 2/3 per week.

CONCLUSION

This review synthesized the components of exercise prescription for sarcopenic older adults which would help practitioners and researchers in selecting the frequency, intensity, duration, type, mode, and progression while prescribing exercises.

EXercise to Prevent frailty and Loss Of independence in insulin treated older people with DiabetEs (EXPLODE): protocol for a feasibility randomised controlled trial (RCT)

INTRODUCTION

There are 3.9 million people in the UK with diabetes. Sarcopenia, increased frailty and loss of independence are often unappreciated complications of diabetes. Resistance exercise shows promise in reducing these complications in older adult diabetes patients. The aim of this feasibility randomised controlled trial is to (1) characterise the physical function, cardiovascular health and the health and well-being of older adults with mild frailty with/without diabetes treated with insulin, (2) to understand the feasibility and acceptability of a 4-week resistance exercise training programme in improving these parameters for those with diabetes and (3) to test the feasibility of recruiting and randomising the diabetic participant group to a trial of resistance training.

METHODS AND ANALYSIS

Thirty adults aged ≥60 years with insulin-treated diabetes mellitus (type 1 or 2), and 30 without, all with mild frailty (3-4 on the Rockwood Frailty Scale) will be recruited. All will complete blood, cardiovascular and physical function testing. Only the diabetic group will then proceed into the trial itself. They will be randomised 1:1 to a 4-week semisupervised resistance training programme, designed to increase muscle mass and strength, or to usual care, defined as their regular physical activity, for 4 weeks. This group will then repeat testing. Primary outcomes include recruitment rate, attrition rate, intervention fidelity and acceptability, and adherence to the training programme. A subset of participants will be interviewed before and after the training programme to understand experiences of resistance training, impact on health and living with diabetes (where relevant) as they have aged. Analyses will include descriptive statistics and qualitative thematic analysis.

ETHICS AND DISSEMINATION

The North East-Newcastle and North Tyneside 2 Research Ethics Committee (20/NE/0178) approved the study. Outputs will include feasibility data to support funding applications for a future definitive trial, conference and patient and public involvement presentations, and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ISRCTN13193281.

Health-Related Functional Fitness within the Elderly Communities of Five European Countries: The in Common Sports Study

(1) Background: The purpose of this study was to analyse the functional fitness and the anthropometric values of older adults participating in the “IN COMMON SPORTS” project. (2) Methods: A total of 418 participants (eastern European Group (GEE, n = 124) and southern European Groups (GES, n = 294) have been evaluated for anthropometric characteristics and fitness. (3) Results: The GES participants presented significant differences in anthropometric values and fitness, with the best values for upper and lower limb strength and aerobic resistance, while those from the GEE presented significantly better values for lower limb flexibility. (4) Conclusion: Older adults present differences in fitness in accordance with their country of residence, with the GES having the best functional fitness.

Strategic Ingestion of High-Protein Dairy Milk during a Resistance Training Program Increases Lean Mass, Strength, and Power in Trained Young Males

BACKGROUND

We evaluated the effects of high-protein dairy milk ingestion on changes in body composition, strength, power, and skeletal muscle regulatory markers following 6 weeks of resistance training in trained young males.

METHODS

Thirty resistance-trained young males (age: 27 ± 3 years; training experience: 15 ± 2 months) were randomly assigned to one of two groups: high-protein dairy milk (both whey and casein) + resistance training (MR; n = 15) or isoenergetic carbohydrate (maltodextrin 9%) + resistance training (PR; n = 15). Milk and placebo were ingested immediately post-exercise (250 mL; 30 g protein) and 30 min before sleep (250 mL; 30 g protein). Before and after 6 weeks of linear periodized resistance training (4 times/week), body composition (bioelectrical impedance), strength, power, and serum levels of skeletal muscle regulatory markers (insulin-like growth factor 1 (IGF-1), growth hormone, testosterone, cortisol, follistatin, myostatin, and follistatin-myostatin ratio) were assessed.

RESULTS

The MR group experienced a significantly higher (p < 0.05) increase in lean mass, strength, and power (upper- and lower-body) than the PR group. Further, IGF-1, growth hormone, testosterone, follistatin, and follistatin-myostatin ratio were significantly increased, while cortisol and myostatin significantly decreased in the MR group than the PR group (p < 0.05).

CONCLUSIONS

The strategic ingestion of high-protein dairy milk (post-exercise and pre-sleep) during 6 weeks of resistance training augmented lean mass, strength, power, and altered serum concentrations of skeletal muscle regulatory markers in trained young males compared to placebo.

Feasibility and acceptability of a milk and resistance exercise intervention to improve muscle function in community-dwelling older adults (MIlkMAN): Pilot study

BACKGROUND

Dietary protein supplementation combined with resistance exercise (RE) may counteract declines in muscle strength, mass, and function (sarcopenia), but the role of whole foods rich in protein, such as milk, is less well understood. In the MIlkMAN study, we aimed to examine the feasibility and acceptability of milk+RE as an intervention for muscle function in community-dwelling older adults, and provide exploratory pilot data for future substantive research in population at risk of sarcopenia.

METHODS

In a parallel groups design, 30 older adults (71.7±3.6 years; 12 women) were randomised into three groups: WM (whole milk 3.6% fat)+RE, SM (skimmed milk 0.3% fat)+RE, and C (isocaloric carbohydrate drink)+RE. RE was performed twice-weekly over 6 weeks in a community gym, followed by the consumption of 500 ml of milk (~20 g protein) or carbohydrate drink immediately after exercise and a further 500 ml at home within the following 4-5 hours. The feasibility and acceptability of the study was determined by calculating recruitment and attendance rates, compliance with the intervention, rating participants' experiences, and recording adverse health events.

RESULTS

The response rate was 49% (out of 400 invitations sent), and the recruitment rate was 73.2% (30 participants recruited out of 41 screened for eligibility). Twenty-nine participants completed the intervention-an attendance rate of 97.1%; 89.7% rated their experience as 'excellent'/very good'. Compliance with taking the drinks was 97.1% (WM), 98.3% (SM), and 95.0% (C); 93.1% rated their drink intake as 'easy'/'very easy' with no adverse effects. Collection of exploratory pilot data to inform future trials was successful. Mean change in grip strength, 5-chair rises, and gait speed were 0.9±3.4 kg, 1.8±2.2 s, 0.1±0.1 m/s, respectively with no differences between the groups.

CONCLUSIONS

This community-based milk+RE intervention was feasible and acceptable to older adults. The study successfully collected pilot data for future substantive research.

Study of the Older Adults' Motivators and Barriers Engaging in a Nutrition and Resistance Exercise Intervention for Sarcopenia: An Embedded Qualitative Project in the MIlkMAN Pilot Study

Objectives: The present study aimed to investigate motivators and barriers to older adults engaging in a nutrition and resistance exercise (RE) intervention for sarcopenia. Methods: We conducted a content analysis of structured interviews with 29 community-dwelling older adults (aged 65–80 years) completing the MIlk Intervention Muscle AgeiNg (MIlkMAN) study. Results: Content analysis revealed that self-perceived improved health, knowledge acquisition in nutrition and exercise, social well-being, professional support in a fun environment, and positive reported outcomes were motivators for engagement in the intervention. Peer encouragement, social bonds, and their retention were motivators to continuing engagement after study completion, especially in widowed women. Barriers to maintenance included affordability, environmental factors, and concerns over negative health outcomes. Discussion: Nutrition and RE interventions for sarcopenia should focus on knowledge acquisition about their health benefits, being enjoyable, and offering social opportunities that have the potential to last beyond the study duration to promote and maintain positive health behaviors.

Milk for Skeletal Muscle Health and Sarcopenia in Older Adults: A Narrative Review

Skeletal muscle aging manifests as a decline in muscle quantity and quality that accelerates with aging, increasing the risk of sarcopenia. Sarcopenia is characterized by a loss of muscle strength and mass, and contributes to adverse health outcomes in older adults. Intervention studies have shown that sarcopenia may be treated by higher protein intake in combination with resistance exercise (RE). In comparison, less is known about the role of whole protein-containing foods in preventing or treating sarcopenia. Liquid milk contains multiple nutrients and bioactive components that may be beneficial for muscle, including proteins for muscle anabolism that, alone or with RE, may have myoprotective properties. However, there is a lack of evidence about the role of milk and its effects on muscle aging. This narrative review considers evidence from three observational and eight intervention studies that used milk or fortified milk, with or without exercise, as an intervention to promote muscle health and function in older adults (aged 50–99 years). The observational studies showed no association between higher habitual milk consumption and muscle-related outcomes. The results of intervention studies using fortified milk in relation to elements of sarcopenia were also negative, with further inconclusive results from the studies using a combination of (fortified) milk and exercise. Although milk contains nutrients that may be myoprotective, current evidence does not show beneficial effects of milk on muscle health in older adults. This could be due to high habitual protein intakes (>1.0 g/kg BW/d) in study participants, differences in the type of milk (low-fat vs whole) and timing of milk consumption, length of interventions, as well as differences in the sarcopenia status of participants in trials. Adequately powered intervention studies of individuals likely to benefit are needed to test the effectiveness of a whole food approach, including milk, for healthy muscle aging.