Interval training versus moderate-intensity continuous training for cardiorespiratory fitness improvements in middle-aged and older adults: a systematic review and meta-analysis

ABSTRACT

Interval training has been promoted as a superior, time-efficient exercise strategy for enhancing cardiorespiratory fitness in the ageing population. This study assessed the effectiveness of interval training compared with that of moderate-intensity continuous training (MICT) for improving cardiorespiratory fitness in middle-aged and older adults. Six databases were systematically searched for studies with exercise interventions (minimum 2-week duration). Meta-analyses were conducted for within-group and between-group comparisons of maximal oxygen uptake (VO_2max). Sub-group analysis was performed using the nature of interval training (high-intensity interval training [HIIT] and sprint interval training [SIT]). Of 3,257 studies, 14 were included (429 participants). Within–group analyses demonstrated significant VO_2max improvements (mL/kg/min) following interval training (mean difference: MD = 2.26; 95% confidence interval [CI] = 1.50–3.02) and MICT (MD = 1.34; 95% CI = 0.45–2.23]. When comparing the modes of training, the gain in VO_2max was significantly greater following interval training (MD = 1.10; CI = 0.55-1.64). Sub–group analysis showed that HIIT (MD = 1.04; CI = 0.21–1.88) and SIT (MD = 1.18; CI = 0.60-1.76) resulted in superior VO_2max gain than MICT. This study provides evidence synthesis for interval training as a viable exercise strategy to improve cardiorespiratory function in healthy ageing.

KEYWORDS:

• HIIT
• interval exercise
• continuous exercise
• aerobic fitness
• public health

Key points

1. Interval training and moderate-intensity continuous training (MICT) both elicited significant cardiorespiratory fitness improvements in middle-aged and older adults

2. The gain in maximal oxygen uptake (VO_2max) was greater following either high-intensity interval training (HIIT) or sprint interval training (SIT) when compared with MICT.

3. This study provides an up-to-date evidence synthesis for interval training as a viable exercise strategy to improve cardiorespiratory function in healthy ageing.

Availability of data and materials

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Systematic review registration number

This study was registered in the International Prospective Register of Systematic Review (PROSPERO; registration number CRD 210814).

Authors’ contributions

EP, WW, RH, and SW designed the research. EP conducted the searches, and EP and WW completed the screening process. EP extracted the data, which were verified by WW and RH. EP performed all statistical analyses. EP, WW, and RH interpreted the data analysis. EP wrote the manuscript with critical input from EP, WW, RH, and SW. All authors have read and approved the final manuscript.

Additional information

Funding

No sources of funding were used to assist in the preparation of this article