The World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases is the largest worldwide event fully dedicated to the clinical and economical aspects of these diseases. Over 3,500 clinicians and international experts attended the Congress in Malaga, Spain in April, jointly organised by the International Osteoporosis Foundation (IOF) and the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO). 

Research and scientific information was shared on epidemiology, pathogenesis, prevention and treatment of these important public health problems. The 2016 Congress featured a symposium with a special focus on the role of dietary protein in sarcopenia, organised by the European Milk Forum (EMF).

Sarcopenia is emerging as perhaps one of the most significant musculoskeletal conditions associated with ageing. It is characterised by a progressive decline in muscle mass and strength that can lead to physical disability, frailty and poor quality of life. It increases the risk of falls and fractures, which in turn cause loss of independence and an increased risk of mortality. 

The sarcopenia symposium at the 2016 Congress was chaired by world expert in osteoporosis and president of the ESCEO, Prof Jean-Yves Reginster and Prof René Rizzoli, from the Faculty of Medicine at Geneva University Hospital. Prof Rizzoli is renowned for his ground breaking research in metabolic bone diseases and, during the conference, he was awarded the Herbert Fleish Medal for excellence in this area. 

The symposium comprised three lectures, presented by invited speakers, with questions from the audience and robust discussions led by both Prof Reginster and Prof Rizzoli.

Sarcopenia causes and consequences

The first lecture was presented by Prof Alfonso Cruz-Jentoft, lead author on a groundbreaking paper with the European Working Group on Sarcopenia in Older People in 2010, which defined sarcopenia and its diagnostic criteria. Prof Cruz-Jentoft explained: “Sarcopenia may best be viewed as a form of organ failure, with muscle being the insufficient organ. The pathophysiology is complex, involving muscular, neural and hormonal factors.” He said that with normal ageing, the quality of muscle fibres slowly deteriorate causing a decline in peak power, muscle shortening speed and elasticity. 

The weakening of muscle fibres that occurs during sarcopenia results from the interaction of several age-related changes, such as loss of anabolic stimuli and sub-clinical inflammation. Prof Cruz-Jentoft said that resistance exercise and adequate protein intake are two of the most important anabolic stimuli for the synthesis of muscle tissue and that these can help to delay the onset of sarcopenia.

He outlined the criteria used in the diagnosis of sarcopenia and said that the condition has three stages: 

Pre-sarcopenia, which is simply a decline in muscle mass with no major consequences

Clinical sarcopenia, which involves a decline in muscle mass coupled with either a marked decline in muscle strength or performance

Severe sarcopenia, which is a loss of muscle mass coupled with a debilitating decline in both muscle strength and performance. 

The progression is usually chronic, going unnoticed for some time but it can develop acutely as a result of other factors such as a hospital admission, Prof Cruz-Jentoft said. “Sarcopenia can be considered ‘primary’ (or age-related) when no other cause is evident apart from advanced age. It can be considered ‘secondary’ when one or more other causes are evident, such as lack of physical activity, impaired nutrition or cachexia related (resulting from malignancy or endocrine disease).”

In clinical practice, muscle mass is usually determined using either bioimpedance analysis (BIA) or dual energy x-ray absorptiometry (DXA). A simple strength test can be performed by a handgrip dynamometer and performance ability can be determined by the short physical performance battery test, gait speed or a get-up-and-go test.

Preventing sarcopenia

The second lecture was given by Dr Lex Verdijk, who is leading cutting edge research on sarcopenia at Maastricht University. “Skeletal muscle represents the most abundant tissue in the human body, accounting for up to 50% of body weight in young adults. Efforts to maintain muscle mass are paramount to healthy ageing, as they help to prevent the functional impairments and declines in metabolic health that are associated with sarcopenia,” said Dr Verdijk. 

In a healthy individual, there is an intricate balance between muscle protein synthesis and breakdown, with about 1-2% of muscle mass being turned over daily. “Physical activity and protein intake work synergistically, thereby optimising net protein balance”. He presented some data from his own research group, showing that an amino acid infusion on its own, could increase muscle synthesis by 35% and combined with an exercise intervention it increased by 100%. 

Dr Verdijk explained that the amount, type and timing of protein ingestion across the day were all important factors and that foods rich in the amino acid, leucine are among the best at stimulating muscle protein synthesis. He said that dairy protein is a high-quality source, due to its leucine content and that increasing milk protein at breakfast has shown a benefit in frail older people. Taking a protein beverage before bed has also shown benefits in older people. 

He said that the dietary recommendations for protein in older people need to be increased from the current level of 0.8g per kg body weight per day to 1.2-1.5g per kg body weight per day (for those with sufficient renal function). While 20g doses of whey protein have been effective for young adults, research indicates that doses of 35-40g may be needed for the same effect in elderly people, due to age-related anabolic resistance. He concluded by stating that nutrition intervention is vital for fracture patients and that it is under used in hospital settings.

Osteosarcopenia: muscle and bone

The final lecture was presented by Dr Véronique Coxam, an expert in the endocrine aspects of musculoskeletal health, from the University of Auvergne, France. Dr Coxam said that in addition to their interconnected roles in locomotion, muscle and bone share many similarities, with both declining after the age of about 50 years. She said that cells in the muscular system secrete many molecules that affect bone, including growth factors and interleukins. Dr Coxam also stated that sarcopenia is a risk factor for osteoporosis, with the risk approximately doubling in people with sarcopenia. 

Given that the frailty associated with sarcopenia increases the risk of falling, it is particularly detrimental in those with osteoporosis, as falling dramatically increases fracture risk. In addition, muscle mass can serve as an added protection to bone in that it can attenuate the force of a fall.

ESCEO president Prof Reginster gave the concluding remarks of the symposium saying that sarcopenia represents an impaired state of health with a high personal toll and that major public health interventions involving exercise promotion and increased protein recommendations for elderly people are needed.

For more details see www.wco-iof-esceo.org