Changes in the Second Ventilatory Threshold Following Individualised versus Standardised Exercise Prescription among Physically Inactive Adults: A Randomised Trial

The second ventilatory threshold (VT₂) is established as an important indicator of exercise intensity tolerance. A higher VT₂ allows for greater duration of higher intensity exercise participation and subsequently greater reductions in cardiovascular disease (CVD) risk. This study aimed to compare the efficacy of standardised and individualised exercise prescription on VT₂ among physically inactive adults. Forty-nine physically inactive male and female participants (48.6 ± 11.5 years) were recruited and randomised into a 12-week standardised (n = 25) or individualised (n = 24) exercise prescription intervention. The exercise intensity for the standardised and individualised groups was prescribed as a percentage of heart rate reserve (HRR) or relative to the first ventilatory threshold (VT₁) and VT₂, respectively. Participants were required to complete a maximal graded exercise test at pre-and post-intervention to determine VT₁ and VT₂. Participants were categorised as responders to the intervention if an absolute VT₂ change of at least 1.9% was attained. Thirty-eight participants were included in the analysis. A significant difference in VT₂ change was found between individualised (pre vs. post: 70.6% vs. 78.7% maximum oxygen uptake (VO₂max)) and standardised (pre vs. post: 72.5% vs. 72.3% VO₂max) exercise groups. Individualised exercise prescription was significantly more efficacious (p = 0.04) in eliciting a positive response in VT₂ (15/19, 79%) when compared to the standardised exercise group (9/19, 47%). Individualised exercise prescription appears to be more efficacious than standardised exercise prescription in eliciting a positive VT₂ change among physically inactive adults. Increasing VT₂ allows for greater tolerance to higher exercise intensities and therefore greater cardiovascular health outcomes.