Table 3. Average values during high-intensity intermittent treadmill runs velocity of running kinematics, spring-mass variables and psychophysiological responses before and after the intervention in LHTL and LHTLH groups. Data are means (±SD).
LHTL LHTLH ANOVA P value (η2)
Before After Before After Group Time Interaction
Running kinematics
    Contact time (s) .179 (.010) .179 (.010) .172 (.011) .170 (.012) .127 (.12) .262 (.07) .225 (.08)
    Aerial time (s) .145 (.013) .145 (.013) .148 (.017) .150 (.015) .499 (.03) .225 (.08) .387 (.04)
    Step frequency (Hz) 3.10 (.14) 3.10 (.14) 3.13 (.22) 3.13 (.21) .667 (.01) .836 (.01) .912 (.01)
    Step length (m) 1.79 (.10) 1.79 (.10) 1.76 (.10) 1.76 (.09) .508 (.03) .901 (.00) .769 (.00)
Dynamics and spring-mass characteristics
    Mean loading rate (BW·s-1) 90.7 (17.2) 91.5 (16.1) 89.3 (17.7) 89.1 (13.8) .800 (.01) .865 (.00) .775 (.01)
    Peak vertical forces (BW) 2.93 (.18) 2.90 (.16) 3.05 (.18) 3.04 (.21) .107 (.14) .479 (.03) .717 (.01)
    CoM vertical displacement (m) .045 (.005) .045 (.005) .044 (.007) .043 (.006) .724 (.01) .292 (.06) .724 (.01)
    Leg compression (m) .154 (.017) .154 (.019) .142 (.013) .138 (.013) .048 (.20) .358 (.05) .422 (.04)
    Vertical stiffness (kN·m-1) 50.8 (5.8) 50.7 (4.1) 53.2 (5.6) 54.1 (5.7) .190 (.09) .737 (.01) .694 (.01)
    Leg stiffness (kN·m-1) 15.0 (1.7) 14.7 (1.6) 16.6 (3.1) 17.0 (3.2) .084 (.16) .903 (.00) .251 (.07)
Psycho-physiological responses
    Heart rate (beats·m-1) 179(9) 174(8) 174(10) 173(11) .515 (.02) .044 (.21) .162 (.11)
    RPE (points) 14.9 (1.6) 14.3 (1.0) 14.7 (1.2) 14.3 (1.6) .840 (.00) .151 (.11) .918 (.00)
BW: Body weight, CoM: Center of mass vertical displacement, RPE: Ratings of perceived exertion. Interval-training treadmill runs consisted of six 30-s runs at 115% of each individuals’ velocity associated with maximal oxygen uptake (20.0 ± 0.6 and 19.8 ± 0.7 km·h-1 in LHTL and LHTLH groups with 30-s passive recovery on an instrumented treadmill.