The effect of krill oil supplementation on skeletal muscle function and size in older adults: A randomised controlled trial.

BACKGROUND & AIMS: The aim of this study was to determine the effect of krill oil supplementation, on muscle function and size in healthy older adults. METHODS: Men and women, aged above 65 years, with a BMI less than 35kg/m2, who participated in less than 1h per week of structured self-reported exercise, were enrolled in the study (NCT04048096) between March 2018 and March 2020. Participants were randomised to either control or krill oil supplements (4g/day) for 6 months in this double blind randomised controlled trial. At baseline, 6 weeks and 6 months, knee extensor maximal torque was measured as the primary outcome of the study. Secondary outcomes measured were grip strength, vastus lateralis muscle thickness, short performance physical battery test, body fat, muscle mass, blood lipids, glucose, insulin, and C-Reactive Protein, neuromuscular (M-Wave, RMS and voluntary activation), and erythrocyte fatty acid composition. RESULTS: A total of 102 men and women were enrolled in the study. Ninety-four participants (krill group (26 women and 23 men) and placebo group (27 women and 18 men)) completed the study (mean (SD): age 71.2 (5.1) years and weight 71.8 (12.3) kg). Six months supplementation with krill oil resulted in, an increase in knee extensor maximal torque, grip strength and vastus lateralis muscle thickness, relative to control (p<0.05). The 6-month treatment effects were 9.3% (95%CI: 2.8, 15.8%), 10.9% (95%CI: 8.3, 13.6%) and 3.5% (95%CI: 2.1, 4.9%) respectively. Increases in erythrocyte fatty acid profile were seen with krill oil for EPA 214% (95%CI: 166, 262%), DHA 36% (95%CI: 24, 48%) and the omega-3 index 61% (95%CI: 49, 73%), relative to control (p < 0.05). Krill oil resulted in an increased, relative to control (p < 0.05), M-Wave of 17% (95%CI: 12.7, 38.1%) but there was no effect of krill oil on RMS, voluntary activation, or on any other secondary outcomes such as performance of the short performance physical battery test or quality of life. CONCLUSION: Krill oil supplementation for 6 months results in statistically and clinically significant increases in muscle function and size in healthy older adults. GOV IDENTIFIER: NCT04048096.

Muscle protein synthesis and muscle/metabolic responses to resistance exercise training in South Asian and White European men.

The aims of the current study, therefore, were to compare (1) free-living MPS and (2) muscle and metabolic adaptations to resistance exercise in South Asian and white European adults. Eighteen South Asian and 16 White European men were enrolled in the study. Free-living muscle protein synthesis was measured at baseline. Muscle strength, body composition, resting metabolic rate, VO2max and metabolic responses (insulin sensitivity) to a mixed meal were measured at baseline and following 12 weeks of resistance exercise training. Free-living muscle protein synthesis was not different between South Asians (1.48 ± 0.09%/day) and White Europeans (1.59 ± 0.15%/day) (p = 0.522). In response to resistance exercise training there were no differences, between South Asians and White Europeans, muscle mass, lower body strength or insulin sensitivity. However, there were differences between the ethnicities in response to resistance exercise training in body fat, resting carbohydrate and fat metabolism, blood pressure, VO2max and upper body strength with responses less favourable in South Asians. In this exploratory study there were no differences in muscle protein synthesis or anabolic and metabolic responses to resistance exercise, yet there were less favourable responses in several outcomes. These findings require further investigation.

The effect of short-duration resistance training on insulin sensitivity and muscle adaptations in overweight men.

NEW FINDINGS: What is the central question of this study? What is the time course of muscular adaptations to short-duration resistance exercise training? What is the main finding and its importance? Short-duration resistance training results in early and progressive increases in muscle mass and function and an increase in insulin sensitivity. ABSTRACT: The aim of the study was to investigate the effects of 6 weeks of resistance exercise training, composed of one set of each exercise to voluntary failure, on insulin sensitivity and the time course of adaptations in muscle strength/mass. Ten overweight men (age 36 ± 8 years; height 175 ± 9 cm; weight 89 ± 14 kg; body mass index 29 ± 3 kg m-2 ) were recruited to the study. Resistance exercise training involved three sessions per week for 6 weeks. Each session involved one set of nine exercises, performed at 80% of one-repetition maximum to volitional failure. Sessions lasted 15-20 min. Oral glucose tolerance tests were performed at baseline and post-intervention. Vastus lateralis muscle thickness, knee-extensor maximal isometric torque and rate of torque development (measured between 0 and 50, 0 and 100, 0 and 200, and 0 and 300 ms) were measured at baseline, each week of the intervention, and after the intervention. Resistance training resulted in a 16.3 ± 18.7% (P < 0.05) increase in insulin sensitivity (Cederholm index). Muscle thickness, maximal isometric torque and one-repetition maximum increased with training, and at the end of the intervention were 10.3 ± 2.5, 26.9 ± 8.3, 18.3 ± 4.5% higher (P < 0.05 for both) than baseline, respectively. The rate of torque development at 50 and 100 ms, but not at 200 and 300 ms, increased (P < 0.05) over the intervention period. Six weeks of single-set resistance exercise to failure results in improvements in insulin sensitivity and increases in muscle size and strength in young overweight men.