The role of muscle tone in metabolic health

Metabolic health refers to how well the body generates and processes energy, taking into account cardiovascular risk, blood sugar regulation, blood pressure, and waist circumference. According to a study based on the National Health and Nutrition Examination Survey, the prevalence of metabolic health in American adults is alarmingly low, posing serious individual and public health concerns. Muscle tone, maintained through physical activity, can be a powerful mediator of insulin sensitivity and overall metabolic health, with short-term benefits stemming from each individual training session and long-term adaptations that improve overall body composition. 

The skeletal muscle is the largest metabolic organ in the human body and plays an important role in metabolic health. It is also regarded as an endocrine and paracrine organ, where muscle-derived signaling proteins, called myokines, facilitate communication between the muscles and other organs, such as the liver, pancreas, skeletal system, adipose tissues, and the cardiovascular system. Myokines such as interleukin 6, myostatin, myonectin, and irisin may impact adipogenesis (the process of creating adipose tissue) and lipid metabolism. Paracrine myokines induced during exercise, such as musclin, may also target intramuscular adipose tissue. During exercise, the muscles use as a source of fuel muscle-stored glycogen and circulating plasma glucose, activating glucose metabolism through insulin-dependent mechanisms and optimizing insulin response and glucose oxidation. Routine exercise further increases skeletal muscle tone, oxidative capacity, and mitochondrial biogenesis, which in turn leads to even greater glucose uptake. Muscles also influence energy and protein metabolism throughout the body by acting as a reservoir of amino acids, which can be released when needed elsewhere in the body. 

An observation study (n = 1,407) found that, among people over 65 years old with normal body mass index, lower muscle mass was a risk factor for metabolic syndrome. Adequate muscle tone may improve metabolic health and mitigate the risk for metabolic disease, including type 2 diabetes, obesity, metabolic syndrome, and non-alcoholic fatty liver disease. 

What are some nutrients that can support muscle tone?

• Collagen peptides support the maintenance of collagen, which is the primary structural component of connective tissues, accounting for as much as 30% of the body’s total protein. Collagen is responsible for muscle flexibility and adaptation and provides structure, support, and strength to muscles, helping them function properly. 
  • Randomized controlled trial (n = 53): male subjects with sarcopenia who were supplemented with collagen peptides following resistance training achieved improved body composition by increasing lean body mass more than the control group. 
  • Randomized controlled trial (n = 77): premenopausal women supplemented with collagen peptides increased their lean body mass, hand-grip strength, and leg strength significantly more than the control group.
• Bioactive peptides from the fava bean (Vicia faba), called natural peptide network NPN_1 (PeptiStrong^TM), were identified using a predictive machine learning approach for their optimized properties, supporting healthy inflammatory responses, muscle health, and protein synthesis. 
  • Clinical study (n = 30): males 30 to 45 years old supplemented with 2.4 g per day of NPN_1 showed improved muscle strength recovery and muscle synthesis and reduced muscle fatigue as compared to a control placebo group.
  • Clinical study (n = 30): compared the effectiveness of the plant-derived NPN_1 to that of a high-quality animal-derived protein reference, milk protein concentrate (MPC), in terms of modulating muscle loss during periods of immobilization and improving protein synthesis during remobilization. This study found that males, 19 to 29 years old, supplemented with 10 g of the fava bean peptides twice daily showed similar muscle recovery results to the group that was supplemented with MCP.
• Creatine is stored in skeletal muscle and involved in muscular contractions. Both muscle strength and creatine may naturally decline with age. 
  • Review study of 180 articles: creatine supplementation may promote intramuscular creatine status, high-intensity exercise capacity, and lean body mass. 
  • Meta-analysis of 22 studies: older adults supplemented with creatine showed increased lean body mass and muscle strength during resistance training. 
• Leucine is an essential amino acid that is considered to be the most anabolic. 
  • The International Society of Sports Nutrition recommends resistance exercise and adequate protein consumption in the range of 2.3 to 3.1 g/kg/day to maximize the retention of lean body mass, where the protein source contains 700 to 3,000 mg of leucine, in addition to a balanced content of all other essential amino acids. 
  • A systematic review of 16 randomized controlled studies found that individuals 65 years or older supplemented with leucine experienced beneficial effects on body weight and lean body mass.
• In addition to a balanced whole foods diet rich in vitamins, minerals, phytonutrients, essential amino acids, and essential fatty acids, some other nutrients that may support muscle tone and metabolic health include β‐hydroxy β‐methylbutyrate (HMB), Vitamin D, and geranylgeraniol pyrophosphate.

Learn more about muscle tone and metabolic health: 

Muscle Tone Matters: The Key to Optimal Body Composition and Metabolic Health

Collagen Peptides to Promote Skeletal Muscle

The Probiotic Connection Between Aging, Muscle Mass, and the Gut Microbiome

By Antonia Toupet, PhD