JMIR Publications

ABSTRACT

Background:

Adults and older adults are recommended to engage in 150 minutes of moderate (MPA) to vigorous (VPA) aerobic physical activity (MVPA) per week, with the heuristic message of 3000 steps in 30 minutes [100 steps per minute (spm)]. However, this message is based on adult populations, with a paucity of research on step rate thresholds that correspond to absolute MVPA (moderate = 3 METs, vigorous = 6 METs) and relative MVPA (moderate = 40% VO2max, vigorous = 60% VO2max) in older persons, who have lower stride lengths and a lower exercise capacity. Also, there is a need to consider the influence of anthropometric differences when quantifying the relationship between step rate and intensity related physical activity.

Objective:

This study assessed absolute and relative MVPA step rate thresholds and anthropometric factors [i.e., height, leg length and body mass index (BMI)] in older adults.

Methods:

Nineteen older adults (7 females; age = 69 ± 2 years, BMI = 26 ± 4 kg/m2) completed a staged treadmill walking protocol: six minutes at 2.4, 3.2, 4.0, 5.6, 6.4 km/hr. Steps were manually counted and VO2 was measured via indirect calorimetry. Aerobic fitness was determined via the submaximal single-stage treadmill protocol.

Results:

When BMI was considered, mixed effects modelling revealed absolute and relative MPA step rate thresholds of 108 spm and 117 spm, respectively. Absolute and relative VPA corresponded to step rates of 135 spm and 132 spm, respectively. Neither height nor leg length improved the ability of the model to predict stepping cadence from METs.

Conclusions:

In general, older adults need to walk faster than 100 spm (i.e., ~110 spm) to reach MPA and in excess of ~130 to achieve VPA, depending on BMI status. Healthcare professionals and researchers should adjust cadence based recommendations for differences in BMI in their older patients and consider using relative intensity to most appropriately tailor their physical activity recommendations.