Level, Uphill, and Downhill Running Economy Values Are Correlated Except on Steep Slopes.

The aim of this study was first to determine if level, uphill, and downhill energy cost of running (ECR) values were correlated at different slopes and for different running speeds, and second, to determine the influence of lower limb strength on ECR. Twenty-nine healthy subjects completed a randomized series of 4-min running bouts on an instrumented treadmill to determine their cardiorespiratory and mechanical (i.e., ground reaction forces) responses at different constant speeds (8, 10, 12, and 14 km·h-1) and different slopes (-20, -10, -5, 0, +5, +10, +15, and +20%). The subjects also performed a knee extensor (KE) strength assessment. Oxygen and energy costs of running values were correlated between all slopes by pooling all running speeds (all r 2 ≥ 0.27; p ≤ 0.021), except between the steepest uphill vs. level and the steepest downhill slope (i.e., +20% vs. 0% and -20% slopes; both p ≥ 0.214). When pooled across all running speeds, the ECR was inversely correlated with KE isometric maximal torque for the level and downhill running conditions (all r 2 ≥ 0.24; p ≤ 0.049) except for the steepest downhill slope (-20%), but not for any uphill slopes. The optimal downhill grade (i.e., lowest oxygen cost) varied between running speeds and ranged from -14% and -20% (all p < 0.001). The present results suggest that compared to level and shallow slopes, on steep slopes ~±20%, running energetics are determined by different factors (i.e., reduced bouncing mechanism, greater muscle strength for negative slopes, and cardiopulmonary fitness for positive slopes). On shallow negative slopes and during level running, ECR is related to KE strength.

Integration of Wearable Sensors Into the Evaluation of Running Economy and Foot Mechanics in Elite Runners.

Running economy, known as the steady-state oxygen consumption at a given submaximal intensity, has been proposed as one of the key factors differentiating East African runners from other running communities around the world. Kenyan runners have dominated middle- and long-distance running events and this phenomenon has been attributed, in part at least, to their exceptional running economy. Despite such speculation, there are no data on running mechanics during real-life situations such as during training or competition. The use of innovative wearable devices together with real-time analysis of data will represent a paradigm shift in the study of running biomechanics and could potentially help explain the outstanding performances of certain athletes. For example, the integration of foot worn inertial sensors into the training and racing of athletes will enable coaches and researchers to investigate foot mechanics (e.g., an accurate set of variables such as pitch and eversion angles, cadence, symmetry, contact and flight times or swing times) during real-life activities and facilitate feedback in real-time. The same technological approach also can be used to help the athlete, coach, sports physician, and sport scientist make better informed decisions in terms of performance and efficacy of interventions, treatments or injury prevention; a kind of "telesport" equivalent to "telemedicine." There also is the opportunity to use this real-time technology to advance broadcasting of sporting events with the transmission of real-time performance metrics and in doing so enhance the level of entertainment, interest, and engagement of enthusiasts in the broadcast and the sport. Such technological advances that are able to unobtrusively augment personal experience and interaction, represent an unprecedented opportunity to transform the world of sport for participants, spectators, and all relevant stakeholders.

How accurate is visual determination of foot strike pattern and pronation assessment.

Nowadays, choosing adequate running shoes is very difficult, due to the high number of different designs. Nevertheless, shoes have two main characteristics to fit runners' technique and morphology: drop and arch support. Retailers' advices are usually based on the visual assessment of the customer's running technique. Such method is subjective and requires an experimented examiner while objective methods require expensive material, such as 3D motion system and pressure insoles. Therefore, the aim of this study was to determine the accuracy of foot strike pattern and pronation assessment using video cameras, compared to a gold standard motion tracking system and pressure insoles. 34 subjects had to run at 8, 12 and 16 Km/h shod and 12 Km/h barefoot during 30 s trials on a treadmill. Agreement between foot strike pattern assessment methods was between 88% and 92%. For pronation, agreement on assessment methods was between 42% and 56%. The results obtained indicate a good accuracy on foot strike pattern assessment, and a high difficulty to determine pronation with enough accuracy. There is therefore a need to develop new tools for the assessment of runner's pronation.