Performance trade-offs and ageing in the ‘world's greatest athletes’

Abstract

The mechanistic foundations of performance trade-offs are clear: because body size and shape constrains movement, and muscles vary in strength and fibre type, certain physical traits should act in opposition with others (e.g. sprint versus endurance). Yet performance trade-offs are rarely detected, and traits are often positively correlated. A potential resolution to this conundrum is that -individual performance trade-offs can be masked by-individual variation in 'quality'. Although there is a current debate on how to unambiguously define and account for quality, no previous studies have partitioned trait correlations at the within- and among-individual levels. Here, we evaluate performance trade-offs among and within 1369 elite athletes that performed in a total of 6418 combined-events competitions (decathlon and heptathlon). Controlling for age, experience and wind conditions, we detected strong trade-offs between groups of functionally similar events (throwing versus jumping versus running) occurring at the among-individual level. We further modelled individual (co)variation in age-related plasticity of performance and found previously unseen trade-offs in throwing versus running performance that manifest through ageing. Our results verify that human performance is limited by fundamental genetic, environmental and ageing constraints that preclude the simultaneous improvement of performance in multiple dimensions. Identifying these constraints is fundamental to understanding performance trade-offs and predicting the ageing of motor function.

Spontaneous activity rates and resting metabolism: Support for the allocation model of energy management at the among‐individual level

“…Related to these points, it would also be informative to evaluate the among‐ and within‐individual correlations between behavioral activities and metabolism early in life, mid‐life and late in life during senescence. The latter requires paired measurements of behaviors and metabolism for several or more measures per individual to begin to partition among‐individual trends from within‐individual trends which may or may not operate in the same direction (for an example of this approach see Careau & Wilson, ).…”

Conflict, compensation, and plasticity: Sex‐specific, individual‐level trade‐offs in green anole (Anolis carolinensis) performance

“…Despite long‐standing interest in trade‐offs involving functional traits, few studies have applied variance partitioning approaches to tease apart the influence of among‐ and within‐individual variation and covariation on phenotypic relationships among different performance abilities (Careau & Wilson, ; ). We adopted this approach here and tested for such correlations among sprinting, biting, and endurance in both male and female green anole lizards.…”

General conclusion to the special issue Moving forward on individual heterogeneity

“…For instance, mixture models are increasingly used to uncover life-history tactics that may occur within a population (Authier et al 2012, Chevallier et al 2013, Fay et al 2016, Hamel et al 2017, 2018 and to partition the variance in lifetime demographic traits into components due to heterogeneity fixed at birth and heterogeneity generated by stochasticity during a life course (Hartemink et al 2017, Jenouvrier et al 2017, Hartemink and Caswell 2018. Joint models are used to assess the full co-variation among traits, thereby improving our understanding of positive and negative relationships among numerous traits (Cam et al 2002, Pavitt et al 2016, Careau and Wilson 2017, Hamel et al 2017. Still, progress is required in terms of both developing these modelling frameworks and communicating them to enhance knowledge transfer.…”