Table 3.
Maximal countermovement jumping.
| Maasai (n = 15) | Controls (n = 12) | 95% C.I. | P | |
|---|---|---|---|---|
| Kinematics | ||||
| Maximal jump height (cm) | 46.5 ± 4.3 | 46.5 ± 6.2 | − 4.2, 4.2 | 0.987 |
| Duration FLXdec (ms) | 114 ± 29 | 172 ± 22 | − 79, − 39 | < 0.001* |
| Duration EXT (ms) | 213 ± 38 | 286 ± 43 | − 105, − 41 | 0.001* |
| ΔBCM FLX (cm) | 24.6 ± 4.2 | 34.8 ± 6.8 | − 15.5, − 4.9 | 0.001* |
| ΔBCM EXT (cm) | 36.1 ± 5.1 | 45.9 ± 8.1 | − 14.4, − 4.3 | 0.001* |
| Hip joint ROM (°) | 81.1 ± 13.3 | 105.8 ± 20.9 | − 38.3, − 11.1 | < 0.001* |
| Knee joint ROM (°) | 80.2 ± 10.8 | 87.2 ± 13.2 | − 16.5, 2.5 | 0.112 |
| Ankle joint ROM (°) | 26.1 ± 5.0 | 25.2 ± 6.2 | − 3.5, 5.3 | 0.657 |
| Kinetics | ||||
| Peak FZ force FLX (N/kg) | 29.2 ± 5.2 | 23.6 ± 1.4 | 2.4, 8.8 | 0.011* |
| Peak FZ force EXT (N/kg) | 29.7 ± 5.3 | 24.0 ± 1.4 | 2.4, 8.7 | 0.010* |
| Mean FZ force EXT (N/kg) | 22.3 ± 2.9 | 19.1 ± 1.5 | 1.3, 5.1 | 0.012* |
| Power, work | ||||
| Peak power EXT (W/kg) | 55.2 ± 8.3 | 49.2 ± 5.7 | 0.2, 11.8 | 0.050* |
| FZ @ peak power (N/kg) | 23.1 ± 3.3 | 19.7 ± 1.5 | 1.3, 5.5 | 0.003* |
| VBCM @ peak power (m/s) | 2.39 ± 0.14 | 2.49 ± 2.18 | − 1.3, 1.1 | 0.119 |
| Mean power EXT (W/kg) | 32.9 ± 5.6 | 27.8 ± 3.3 | 1.3, 8.9 | 0.001* |
| Work FLX (J/kg) | 6.68 ± 0.65 | 7.29 ± 1.19 | − 1.4, 0.1 | 0.001* |
| Work EXT (J/kg) | 2.41 ± 5.3 | 3.42 ± 0.69 | − 4.2, 2.2 | 0.008* |
| Ratio work EXT/work FLX | 2.90 ± 0.37 | 2.35 ± 0.22 | 0.3, 0.8 | < 0.001* |
| RFD, stiffness, efficiency | ||||
| RFD (N/s kg) | 219.9 ± 199.2 | 88.6 ± 28.2 | 11.5, 251.1 | 0.001* |
| LLS (N/m kg) | 245.6 ± 135.1 | 96.0 ± 25.6 | 67.8, 231.4 | 0.001* |
| RSI FLXdec + EXT (m/s) | 1.48 ± 0.36 | 1.01 ± 0.17 | 0.2, 0.7 | < 0.001* |
| JH/work (cm/(J/kg)) | 5.10 ± 0.50 | 4.51 ± 0.45 | 0.2, 1.0 | 0.004* |
Group mean ± SD. 95% confidence interval (C.I.) for differences between means.
FLXdec, deceleration during flexion phase; FLX, flexion phase (BCM moving downwards); EXT, extension phase (BCM moving upwards); ΔBCM, displacement body center of mass. Joint excursion is presented as maximal flexion (hip and knee joint) and maximal dorsiflexion (ankle joint) ROM during the push off phase relative to in situ joint position. Fz force, vertical ground reaction force; VBCM, BCM velocity; RFD, rate of Fz development measured from onset of FLXdec to + 50 ms; LLS, lower limb stiffness calculated as ΔFz /ΔBCM; RSI FLXdec + EXT, Reactive Strength Index calculated as jumpheight (m)/duration of the FLXdec + EXT phases; JH/Work, maximal vertical jump height normalized to work produced in the extension phase (vertical jump efficiency).
*Denotes significant group difference.