Author(s): DEBOUTTE, J., ALCAZAR, J., WALKER, S., DELECLUSE, C., VAN ROIE, E. , Institution: KU LEUVEN, Country: BELGIUM, Abstract-ID: 1729

INTRODUCTION:
Resistance exercise is the primary therapeutic strategy to counteract age-related declines in muscle function. To individualize exercise intensity, training loads are often prescribed based on an individual’s one-repetition maximum (1-RM) [1]. Despite the excellent reliability of 1-RM measurements [2], the protocol is time-consuming and may enhance the risk of injuries, especially in older adults [3]. Consequently, various approaches for estimating 1-RM, and thus accurate training intensity, have been introduced. The load-velocity (L-v) profile has emerged as one potential method, considering that movement velocity can accurately predict relative load [4]. Therefore, the aim of this analysis was to determine how accurately the 1-RM of older men can be estimated from their individual L-v profile.
METHODS:
Sixty-four men (66.9 ± 5.4 years old) completed the L-v profiling protocol on a pneumatic leg press device [5]. The protocol started with a maximal isometric test, followed by explosive concentric leg extensions at five pre-fixed increasing loads. Each load was a set percentage of the maximal isometric force, and participants performed 2 to 3 attempts per load. For each of the five loads, the attempt with the highest mean velocity was selected, and the load and velocity values of that attempt were used to create each participant’s individualized linear regression equation. Following the five sub-maximal contractions, all participants performed additional single repetitions until reaching 1-RM. Each individual’s velocity at 1-RM was recorded and used to calculate the group’s mean velocity at 1-RM. This value (0.10 ± 0.07 m/s) was used as an input in the individualized L-v equations to finally obtain each individual’s estimated 1-RM.
RESULTS:
Estimated 1-RM was slightly higher than measured 1-RM, but the difference was not significant (-0.5 ± 6.4 kg, p=0.525). In addition, the methods showed excellent absolute agreement (ICC=0.92, p<0.001). Despite the strong relationship at a group level, there was substantial inter-individual variability in the agreement between the two methods. The large difference between the estimated and measured 1-RM in some individuals was reflected in the Bland-Altman plot, as well as in the linear regression analysis that yielded a standard error of estimate of 6.3 kg.
CONCLUSION:
Estimating 1-RM from L-v profiling provides a low risk, time-efficient alternative for prescribing resistance training load. The results are promising at a group level but may not be generalizable to all individuals and should therefore be interpreted with caution.
REFERENCES:
1. Thompson, S.W., et al. Sports Med, 2020. 50(5): p. 919-938.
2. McMaster, D.T., et al. Sports Med, 2014. 44(5): p. 603-23.
3. Niewiadomski, W., et al. J Hum Kinet, 2008. 19(1): p. 109-120.
4. González-Badillo, J.J. and L. Sánchez-Medina. Int J Sports Med, 2010. 31(5): p. 347-52.
5. Poffé, C., et al. J Sports Sci Med, 2023. 22(2): p. 345-357.