“Whip from the hip”: thigh angular motion, ground contact mechanics, and running speed

Abstract

During high-speed running, lower limb vertical velocity at touchdown has been cited as a critical factor needed to generate large vertical forces. Additionally, greater leg angular velocity has also been correlated with increased running speeds. However, the association between these factors has not been comprehensively investigated across faster running speeds. Therefore, this investigation aimed to evaluate the relationship between running speed, thigh angular motion, and vertical force determinants. It was hypothesized that thigh angular velocity would demonstrate a positive linear relationship with both running speed and lower limb vertical velocity at touchdown. A total of 40 subjects (20 males, 20 females) from various athletic backgrounds volunteered and completed 40 m running trials across a range of sub-maximal and maximal running speeds during one test session. Linear and angular kinematic data were collected from 31–39 m. The results supported the hypotheses, as across all subjects and trials (range of speeds: 3.1–10.0 m s−1), measures of thigh angular velocity demonstrated a strong positive linear correlation to speed (all R2>0.70, p<0.0001) and lower limb vertical velocity at touchdown (all R2=0.75, p<0.0001). These findings suggest thigh angular velocity is strongly related to running speed and lower limb impact kinematics associated with vertical force application.

Hip Torque Is a Mechanistic Link Between Sprint Acceleration and Maximum Velocity Performance: A Theoretical Perspective

“…While running at or near maximum velocity, each thigh rotates about the hip axis with sinusoidal motion (Mann et al, 1986 ; Clark et al, 2020 ). The angular motion of the thigh coincides with the angular motion of the leg when extended during swing phase.…”

“…In the first section of Table 1 , we evaluated Equation 8 across an array of input values for t c , θ t , and f str based on previously published data (Nagahara et al, 2014 ; Mann and Murphy, 2018 ; Murphy et al, 2021 ; Clark et al, 2020 ) to establish the general range of τ values under normal sprint conditions. Note that mathematically, stride frequency is a function of contact and flight time, and given relatively consistent flight times across a range of top speeds (Weyand et al, 2000 ), briefer t c will be associated with faster f str .…”

“… Variables: h b = body height, m b = body mass, L leg = leg length, t c = ground-contact time at maximum velocity, θ t = total thigh range of motion at maximum velocity, f str = stride frequency at maximum velocity, v 0 = maximum velocity limit, a 0 = maximum sprint acceleration limit equivalent to F 0 normalized to body mass (N/kg), and τ = time constant. Values for input variables t c , θ t , and f str are based on Nagahara et al ( 2014 ); Mann and Murphy ( 2018 ); Clark et al ( 2020 ) and Murphy et al ( 2021 ) to correspond with maximum velocities ranging from approximately 7.0 to 12.0 m/s . Output variables are calculated based on input variables using Equations 6–8 .…”

“…Anthropometric data for height ( h b ) and body mass ( m b ) were based on a body mass index (BMI = m b /h ) of ~23 kg/m 2 and leg length was calculated as L leg = 0.53● h b (Winter, 2009 , Figure 4.1). Kinematic values for t c , θ t , and f str were based on previously published data (Nagahara et al, 2014 ; Mann and Murphy, 2018 ; Murphy et al, 2021 ; Clark et al, 2020 ) for fast, intermediate, and slow athletes over a range of body dimensions. The resultant τ values maintained a range from 1.15 to 1.25 s across the range of input values.…”

“…After the first few steps, runners quickly establish a thigh angular range of motion and stride frequency that is nearly constant (Nagahara et al, 2014 , 2017 ). Runners with faster maximum sprinting speed generally exhibit larger values of maximum thigh range of motion and frequency (Clark et al, 2020 ). This is indicative of the rapid thigh reversal occurring at peak flexion and extension (Mann et al, 1986 ; Nagahara et al, 2017 ; Clark et al, 2020 ; Kakehata et al, 2021 ), and can be quantified by the maximum angular acceleration value (Clark et al, 2021 ) and corresponding torque.…”