JMIR Publications

ABSTRACT

Background:

Sarcopenia is the age-related loss of skeletal muscle mass and function and may exist in early middle age. Previous research in this area has focused on resistance training (RT) in older individuals, however there is a lack of intervention trials in middle-aged adults with low relative appendicular lean soft tissue mass who may be a risk for sarcopenia in older age.

Objective:

This current randomized controlled trial aims to determine the effects of a high-intensity interval training (HIIT) intervention on appendicular lean soft tissue mass in middle-aged adults with low relative appendicular lean soft tissue mass.

Methods:

A 40-week single-blinded randomized controlled trial will be conducted in 84 middle-aged adults with low appendicular lean soft tissue mass in the wider Dunedin area, New Zealand. Participants will be randomly allocated to receive either a group-based, 20-week HIIT intervention program or a single, 60-minute, education session on current exercise recommendations. After the first 20-weeks, both groups will be given a 20-week home-program. The study will assess primary and secondary outcome measures including body composition (regional and whole-body lean soft tissue mass, fat mass, percent body fat, measured by dual x-ray absorptiometry), blood biomarkers (cortisol, creatinine, C-reactive protein, lipid profile, haemoglobin), physical fitness (VO2max, blood pressure), physical activity (accelerometery), physical function (handgrip strength, sit to stand, gait speed and quadriceps strength), and self-reported questionnaires (health outcomes, self-efficacy, perceived enjoyment of physical activity and multifactorial lifestyle) at baseline, 20-weeks and 40-weeks. Physical function and self-reported questionnaires will also be measured at 10-weeks. The primary outcome measure, appendicular lean soft tissue mass, will be assessed at baseline, 20-weeks and 40-weeks. Analyses will be performed using intention to treat principles, comparing the outcomes resulting from the intervention, using linear mixed models.

Results:

Ethical approval for the current study was obtained from The University of Otago Human Ethics Committee on the 10th of December 2018. Participant recruitment started on the 11th of February 2019 and was completed on the 14th of May 2019. Data collection started on the 25th of February 2019 and was completed on the 28th of February 2020. Results are expected to be published in January 2021.

Conclusions:

HIIT is a time-efficient form of exercise, enabling busy middle-aged adults to meet physical activity recommendations while maximizing training results. The findings can inform the development of future, prevention focussed, interventions, aimed at counteracting the high prevalence of sarcopenia in the ageing population. Clinical Trial: This present study was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001778279) on October 30th, 2018.