Human locomotion on ice: the evolution of ice-skating energetics through history

Mechanical determinants of forward skating sprint inferred from off- and on-ice force-velocity evaluations in elite female ice hockey players

This study aimed to investigate the correlations between players' mechanical capacities determined during off- and on-ice tests. Whole body force-velocity relationships were assessed in elite female ice hockey players (n = 17) during jumping [squat jump (SJ)], running (5 and 30 m) and skating (5 and 40 m) sprint tasks. Mechanical capacities estimates include relative maximal theoretical force (F_0rel), velocity (V₀), power (P_maxrel), slope of the linear relationship between force relative to body mass and velocity (S_FVrel), maximal horizontal component of the ground reaction force to the corresponding resultant force (RF_max) and minimal rate of decrease of this ratio (D_RF). On-ice mechanical capacities (F_0rel, P_maxrel, RF_max and D_RF) largely-to-very largely correlated with 40-m skating split time (r ranging from 0.82 for D_RF to -0.91 for P_maxrel; p < 0.001). Performance variables (SJ height, 30-m running and 40-m forward skating split time) and P_maxrel demonstrated the largest associations between jumping, running and skating tasks (r ranging from -0.81 for 30-m sprint running time to 0.92 for SJ height; p < 0.001). Small (V₀, S_FVrel, D_RF and force-velocity deficit) to very large (P_maxrel) correlations (r ranging from 0.58 to 0.72; p < 0.05) were obtained between mechanical variables inferred from off- and on-ice force-velocity tests. The capacity to generate high amounts of horizontal power and effective horizontal force during the first steps on the ice is paramount for forward skating sprint performance. Mechanical capacities determined during forward skating sprint could be considered in ice hockey testing to identify fitness and/or technical/training requirements.

A review of the physics of ice surface friction and the development of ice skating

Our walking and running movement patterns require friction between shoes and ground. The surface of ice is characterised by low friction in several naturally occurring conditions, and compromises our typical locomotion pattern. Ice skates take advantage of this slippery nature of ice; the first ice skates were made more than 4000 years ago, and afforded the development of a very efficient form of human locomotion. This review presents an overview of the physics of ice surface friction, and discusses the most relevant factors that can influence ice skates' dynamic friction coefficient. It also presents the main stages in the development of ice skating, describes the associated implications for exercise physiology, and shows the extent to which ice skating performance improved through history. This article illustrates how technical and materials' development, together with empirical understanding of muscle biomechanics and energetics, led to one of the fastest forms of human powered locomotion.

Limitations imposed by wearing armour on Medieval soldiers' locomotor performance

In Medieval Europe, soldiers wore steel plate armour for protection during warfare. Armour design reflected a trade-off between protection and mobility it offered the wearer. By the fifteenth century, a typical suit of field armour weighed between 30 and 50 kg and was distributed over the entire body. How much wearing armour affected Medieval soldiers' locomotor energetics and biomechanics is unknown. We investigated the mechanics and the energetic cost of locomotion in armour, and determined the effects on physical performance. We found that the net cost of locomotion (C(met)) during armoured walking and running is much more energetically expensive than unloaded locomotion. C(met) for locomotion in armour was 2.1-2.3 times higher for walking, and 1.9 times higher for running when compared with C(met) for unloaded locomotion at the same speed. An important component of the increased energy use results from the extra force that must be generated to support the additional mass. However, the energetic cost of locomotion in armour was also much higher than equivalent trunk loading. This additional cost is mostly explained by the increased energy required to swing the limbs and impaired breathing. Our findings can predict age-associated decline in Medieval soldiers' physical performance, and have potential implications in understanding the outcomes of past European military battles.