High-Intensity Interval Training in Older Adults: a Scoping Review

Abstract

High-intensity interval training (HIIT) is an increasingly popular form of aerobic exercise which includes bouts of high-intensity exercise interspersed with periods of rest. The health benefits, risks, and optimal design of HIIT are still unclear. Further, most research on HIIT has been done in young and middle-aged adults, and as such, the tolerability and effects in senior populations are less well-known. The purpose of this scoping review was to characterize HIIT research that has been done in older adults including protocols, feasibility, and safety and to identify gaps in the current knowledge. Five databases were searched with variations of the terms, “high-intensity interval training” and “older adults” for experimental or quasi-experimental studies published in or after 2009. Studies were included if they had a treatment group with a mean age of 65 years or older who did HIIT, exclusively. Of 4644 papers identified, 69 met the inclusion criteria. The average duration of training was 7.9 (7.0) weeks (mean [SD]) and protocols ranged widely. The average sample size was 47.0 (65.2) subjects (mean [SD]). Healthy populations were the most studied group (n = 30), followed by subjects with cardiovascular (n = 12) or cardiac disease (n = 9), metabolic dysfunction (n = 8), and others (n = 10). The most common primary outcomes included changes in cardiorespiratory fitness (such as VO2peak) as well as feasibility and safety of the protocols as measured by the number of participant dropouts, adverse events, and compliance rate. HIIT protocols were diverse but were generally well-tolerated and may confer many health advantages to older adults. Larger studies and more research in clinical populations most representative of older adults are needed to further evaluate the clinical effects of HIIT in these groups.

Equipment-free, unsupervised high intensity interval training elicits significant improvements in the physiological resilience of older adults

“…However, high-intensity interval training (HIIT) appears to confer improvements commonly associated with both aerobic and resistance exercise training [ 22 ], whilst also addressing a commonly cited barrier to exercise uptake and adherence, “lack of time” [ 23 ]. Beyond “time”, older adults also frequently cite their age and “poor health” as barriers to exercise [ 24 ], despite a significant body of literature evidencing the benefits of all types of exercise training (aerobic: [ 25 , 26 ], resistance: [ 21 , 27 ], HIIT: [ 28 , 29 ]) for even the oldest old [ 30 ]. Further, the Generation 100 randomised control trial has demonstrated that older adults can perform both aerobic exercise and HIIT without strict supervision [ 31 , 32 ], suggesting that home-based, time-efficient HIIT without the need for specialist equipment may prove a promising strategy to improve the physiological resilience of older adults, especially at a time when access and desire to attend specialist exercise facilities (i.e., gyms and community classes) may be at an all-time low.…”

The Effects of High-Intensity Interval Training (HIIT) on Fall Risk Factors in Healthy Older Adults: A Systematic Review

“…Based on the current results, a conclusion regarding which modality is most favorable to reduce fall risk in healthy older individuals cannot be reached. Yet, previous studies have shown that the cycle ergometer was the most common type of HIIT instrument used among older persons, followed by treadmill walking [59]. Furthermore, previous reviews recommended cycling (cycle ergometer) as an effective HIIT modality to improve cardiometabolic and cardiovascular health in older persons, including additional benefits in terms of accessibility, safety, and decreased stress on joints [59][60][61].…”

Age-dependent impact of two exercise training regimens on genomic and metabolic remodeling in skeletal muscle and liver of male mice

“…Most research on HIIT has been done in young and middle-aged subjects, and as such, the effects in senior populations are less known. Most common primary outcomes in the HIIT studies describe changes in cardiorespiratory fitness (such as VO 2 peak) as well as feasibility and safety of the protocols 49 . The transcriptomic and, more specifically, metabolomic changes induced by HIIT in old individuals are largely unknown, with few exceptions 50 where levels of several genes related to mitochondria, insulin signaling, and muscle growth were downregulated with age in skeletal muscle biopsies.…”