Worldwide estimates predict 2 billion people will be aged over 65 years by 2050. A major current challenge is maintaining mobility and quality of life into old age. Impaired mobility is often a precursor of functional decline, disability and loss of independence. Sarcopenia which represents the age-related decline in muscle mass is a well-established factor associated with mobility limitations in older adults. However, there is now evidence that not only changes in muscle mass but other factors underpinning muscle quality including composition, metabolism, aerobic capacity, insulin resistance, fat infiltration, fibrosis and neural activation may also play a role in the decline in muscle function and impaired mobility associated with ageing. Importantly, changes in muscle quality may precede loss of muscle mass and therefore provide new opportunities for the assessment of muscle quality particularly in middle-aged adults who could benefit from interventions to improve muscle function. This review will discuss the accumulating evidence that in addition to muscle mass, factors underpinning muscle quality influence muscle function and mobility with age. Further development of tools to assess muscle quality in community settings is needed. Preventative diet, exercise or treatment interventions particularly in middle-aged adults at the low end of the spectrum of muscle function may help preserve mobility in later years and improve healthspan.

The differential ability of various milk protein fractions to stimulate muscle protein synthesis (MPS) has been previously described, with whey protein generally considered to be superior to other fractions. However, the relative ability of a whole milk protein to stimulate MPS has not been compared to whey. Sixteen healthy middle-aged males ingested either 20 g of milk protein (n = 8) or whey protein (n = 8) while undergoing a primed constant infusion of ring ¹³C₆ phenylalanine. Muscle biopsies were obtained 120 min prior to consumption of the protein and 90 and 210 min afterwards. Resting myofibrillar fractional synthetic rates (FSR) were 0.019% ± 0.009% and 0.021% ± 0.018% h⁻¹ in the milk and whey groups respectively. For the first 90 min after protein ingestion the FSR increased (p < 0.001) to 0.057% ± 0.018% and 0.052% ± 0.024% h⁻¹ in the milk and whey groups respectively with no difference between groups (p = 0.810). FSR returned to baseline in both groups between 90 and 210 min after protein ingestion. Despite evidence of increased rate of digestion and leucine availability following the ingestion of whey protein, there was similar activation of MPS in middle-aged men with either 20 g of milk protein or whey protein.

Background: Natural food supplements with high flavonoid content are often claimed to promote weight-loss and lower plasma cholesterol in animal studies, but human studies have been more equivocal. The aim of this study was firstly to determine the effectiveness of natural food supplements containing Glycine max leaves extract (EGML) or Garcinia cambogia extract (GCE) to promote weight-loss and lower plasma cholesterol. Secondly to examine whether these supplements have any beneficial effect on lipid, adipocytokine or antioxidant profiles. Methods: Eighty-six overweight subjects (Male:Female = 46:40, age: 20~50 yr, BMI > 23 < 29) were randomly assigned to three groups and administered tablets containing EGML (2 g/day), GCE (2 g/day) or placebo (starch, 2 g/day) for 10 weeks. At baseline and after 10 weeks, body composition, plasma cholesterol and diet were assessed. Blood analysis was also conducted to examine plasma lipoproteins, triglycerides, adipocytokines and antioxidants. Results: EGML and GCE supplementation failed to promote weight-loss or any clinically significant change in %body fat. The EGML group had lower total cholesterol after 10 weeks compared to the placebo group (p < 0.05). EGML and GCE had no effect on triglycerides, non-HDL-C, adipocytokines or antioxidants when compared to placebo supplementation. However, HDL-C was higher in the EGML group (p < 0.001) after 10 weeks compared to the placebo group. Conclusions: Ten weeks of EGML or GCE supplementation did not promote weight-loss or lower total cholesterol in overweight individuals consuming their habitual diet. Although, EGML did increase plasma HDL-C levels which is associated with a lower risk of atherosclerosis.

Echinochrome A (Echi A) improves mitochondrial function in the heart; however, its effects on skeletal muscle are still unclear. We hypothesized that Echi A administration during short-term exercise may improve exercise capacity. Twenty-four male Sprague-Dawley rats were randomly divided into the following groups: control group (CG), Echi A-treated group (EG), aerobic exercise group (AG), and aerobic exercise treated with Echi A group (AEG) (n = 6 per group). Echi A was administered intra-peritoneally (0.1 mg/kg of Echi A in 300 µL phosphate-buffered saline) daily 30 min before each exercise training. The AG and AEG groups performed treadmill running (20 m/min, 60 min/day) five days/week for two weeks. The exercise capacity was significantly higher in the AG and AEG groups compared to other groups. Interestingly, the exercise capacity increased more effectively in the AEG group. The body weight in the EG tended to be slightly lower than that in the other groups. There were no significant changes in the plasma lipids among the groups. However, the gastrocnemius muscle mitochondria content was greater in the EG and AEG groups. These findings show that Echi A administration after short-term endurance training enhances exercise capacity, which was associated with an increase in skeletal muscle mitochondrial content.