Intensity, repetitiveness, and directionality of habitual adolescent mobility patterns influence the tibial diaphysis morphology of athletes

Abstract

Mobility patterns affect the loads placed on the lower limbs during locomotion and may influence variation in lower limb diaphyseal robusticity and shape. This relationship commonly forms the basis for inferring mobility patterns from hominin fossil and skeletal remains. This study assesses the correspondence between athletic histories, varying by loading intensity, repetition and directionality, measured using a recall questionnaire, and peripheral quantitative computed tomography-derived measurements of tibial diaphysis rigidity and shape. Participants included male university varsity cross-country runners (n = 15), field hockey players (n = 15), and controls (n = 20) [mean age: 22.1 (SD +/- 2.6) years]. Measurements of tibial rigidity (including J, %CA, Imax, Imin, and average cortical thickness) of both runners and field hockey players were greater than controls (P < or = 0.05). Differences in tibial shape (Imax/Imin, P < or = 0.05) between runners and hockey players reflect pronounced maximum plane (Imax) rigidity in runners, and more symmetrical hypertrophy (Imax, Imin) among hockey players. This corresponds with the generally unidirectional locomotor patterns of runners, and the multidirectional patterns of hockey players. These results support the relationship between mobility and tibial diaphysis morphology as it is generally interpreted in the anthropological literature, with greater levels of mobility associated with increased diaphyseal robusticity and shape variation. Although exercise intensity may be the primary influence on these properties, the repetitiveness of the activity also deserves consideration. In conclusion, bone morphological patterns can reflect habitual behaviors, with adaptation to locomotor activities likely contributing to variation in tibial rigidity and shape properties in archaeological and fossil samples.

Gradual decline in mobility with the adoption of food production in Europe

“…Changes in bone shape of this kind strongly imply localized modeling/remodeling resulting from specific mechanical stimuli (20). Despite some partially contrary evidence in cursorial animals (43), which may be under special constraints (20), a number of both experimental and observational studies of humans support the association between preferential strengthening of the lower limb bones in the A-P plane and greater mobility (30,(34)(35)(36)(37)(38). Thus, our results imply a major reduction in mobility in both sexes beginning in the Neolithic.…”

“…It is known that long bone diaphyseal cortices react to imposed mechanical loadings throughout life, changing their cross-sectional geometry to adapt to altered strain magnitudes and distributions, which in turn are dependent on behavioral use of the limbs (20-22, 30, 31). For example, vigorous exercise in humans greatly increases bending strains in the tibia (32,33) and is associated with preferential strengthening in the direction of movement, i.e., running and jumping lead to increases in A-P/M-L strength (30,34,35). Increased A-P/M-L bending strength of the lower limb bones also characterizes more terrestrially mobile populations or subpopulations (36)(37)(38).…”

Skull and limb morphology differentially track population history and environmental factors in the transition to agriculture in Europe

“…Only those populations living in extremely cold climatic conditions appear to have been affected by non-neutral directional climatic adaptation [27,29,32]. However, in the case of the postcranial skeleton, most studies have suggested relatively potent (non-neutral) effects of climatic adaptation [33][34][35][36][37][38], plasticity related to habitual activity [37,39,40] and the effects of nutritional or environmental stress on growth [41][42][43]. However, there is evidence to suggest that the morphology of some regions of the postcranium (i.e.…”

Femoral Functional Adaptation: A Comparison Between Hunter Gatherers and Farmers Using Geometric Morphometrics

“…Several evidences support the idea that bone undergoes mechanical adaptation: a) studies with athletes that show an increased bone strength; b) experimental studies with animals that are submitted to vigorous exercise regimens or movement constraints; c) studies of limb disuse (e.g. pathology, zero gravity, immobility) (Haapasalo et al, 2000;Robling et al, 2000;Shaw & Stock, 2009a, 2009b. Thereby an increased strain will stimulate deposition of new bone tissue which strengthen the bone and consequently reduces strain, while decreased strain (e.g.…”