Effects of Short- and Long-Term Detraining on Maximal Oxygen Uptake in Athletes: A Systematic Review and Meta-Analysis

Abstract

VO2max, a gold standard for evaluating cardiorespiratory fitness, can be enhanced by training and will gradually decrease when training stops. This study, which followed the Cochrane Collaboration guidelines, is aimed at assessing the effect of short- and long-term detraining on trained individuals' VO2max through a systematic review and meta-analysis and performed a subgroup analysis to evaluate the effects of different ages, detraining formats, and training statuses on VO2max variation between short- and long-term training cessation. Web of Science, SPORTDiscus, PubMed, and Scopus, four databases, were searched, from which 21 of 3315 potential studies met the inclusion criteria. Significant decreases in VO2max were identified after short-term training cessation (ES=-0.62 [95% CI -0.94; -0.31], p<0.01; within-group I2=35.3%, Egger's test=-1.22, p=0.335) and long-term training cessation (ES=-1.42 [95% CI -1.99; -0.84], p<0.01; within-group I2=76.3%, Egger's test=-3.369, p<0.01), which shows that the detraining effect was found to be larger on VO2max in long-term training cessation than in short-term training cessation (Q=6.5, p=0.01). However, there was no significant difference regarding VO2max change between 30-90 days detraining and larger than 90 days detraining (Q=0.54, p=0.46) when conducting subgroup analysis. In addition, younger (<20) individuals showed a greater reduction in VO2max after long-term detraining than adult individuals (Q=5.9, p=0.05), and athletes with higher trained-state VO2max showed a significant decline in VO2max after long-term detraining compared with the lower trained-state group (Q=4.24, p=0.03). In conclusion, both short- and long-term training cessation have a detrimental effect on VO2max, and a greater impact on VO2max was found in long-term training cessation compared to short-term training cessation; however, there was no significant change in VO2max when the duration of training cessation was more than 30 days. To buffer the detrimental effects of detraining, especially long-term training cessation, performing some physical exercise during training cessation can effectively weaken detraining effects. Thus, to prevent athlete's VO2max from decreasing dramatically from detraining, athletes should continue performing some physical exercise during the cessation of training.