# Changes in Joint Power and Energetics during a Sport-Specific Jumping Fatigue Protocol
## 3 Results  
Participants performed \(175\pm 85\) jumps (mean \(\pm\) standard deviation) before they were classified as being fatigued. A sample fatigue jump curve is shown in Figure 2, with the total number of jumps divided into five different sections and the three consecutive jumps below 88% of their maximum jump height highlighted in red. Peak joint power, angular velocity at peak power, and joint moment at peak power of the ankle, knee, and hip are shown in Figure 3. At the ankle joint, a significant decrease in peak power (\(p\) = 0.011, ES = 0.627) occurred during the fatigued jumps due to a significant decrease in ankle plantar flexion angular velocity at peak power (\(p\) = 0.003, ES = 0.747). A trend was also present in the 81-100% segment, with peak ankle power being decreased (\(p\) = 0.063, ES = 0.442), and with a decrease in the ankle plantar flexion velocity at peak power (\(p\) = 0.053, ES = 0.460). At the knee joint, a significant increase in the knee extension moment at peak power occurred at 21-40% (\(p\) < 0.001, ES = 1.823) with a corresponding increase in the knee joint peak power at 21-40% (\(p\) = 0.020, ES = 0.569). At the hip joint, a significant decrease in the hip extension angular velocity at peak power occurred at 61-80% (\(p\) = 0.004, ES = 0.730), at 81-100% (\(p\) = 0.040, ES = 0.494), and during the final three fatigued jumps (\(p\) = 0.049, ES = 0.470). The peak power at the hip was significantly reduced at 61-80% (\(p\) = 0.004, ES = 0.757) and during the fatigued jumps (\(p\) = 0.044, ES = 0.481), with the trend of being reduced during 81-100% of the jump protocol (\(p\) = 0.057, ES = 0.452). Joint energetics are shown in Figure 4. The ankle joint had a significant increase in the energy absorbed at 61-80% (\(p\) = 0.028, ES = 0.533), an increase in the energy generated (\(p\) = 0.006, ES = 0.693), and an increase in net energy (\(p\) = 0.045, ES = 0.599) at 21-40%, while the energy generated (\(p\) = 0.010, ES = 0.640 and \(p\) = 0.045, ES = 0.479) and net energy (\(p\) = 0.001, ES = 0.829 and \(p\) = 0.011, ES = 0.629) decreased at 81-100% and during the final  
Figure 3: Ankle, knee, and hip joint angular velocity at peak power (**left**), joint moment at peak power (**center**), and peak power (**right**) during the different phases of the vertical jump fatigue protocol. Bolded asterisks represent a significant difference from the previous jump phase. Figure 2: A jump fatigue curve of a representative athlete. The three red dots represent the three consecutive jumps that were below 88% of the participant’s maximum jump height, indicating the athlete was fatigued. fatigued jumps. At the knee joint, significant increases in the energy absorbed (\(p\) = 0.005, ES = 0.494) and energy generated (\(p\) = 0.039, ES = 0.710) were present at 21-40%, while a significant decrease in the energy absorbed (\(p\) = 0.020, ES = 0.566) occurred at 81-100%. At the hip joint, no changes in joint energy absorbed were present, while a significant reduction in the energy generated (\(p\) = 0.024, ES = 0.548 and \(p\) = 0.047, ES = 0.475) and net energy (0.049, ES = 0.469 and \(p\) = 0.005, ES = 0.705) occurred at 81-100% and during the three final fatigued jumps. Additional kinetic data are shown in Table 1. The vertical ground reaction impulse was significantly reduced during the final fatigued jumps (\(p\) = 0.0329, ES = 0.514). Jump time was significantly reduced during 20-40% (\(p\) = 0.049, ES = 0.471), with trends of having increased during 60-80% (\(p\) = 0.080, ES = 0.414) and then reduced during the final three fatigued jumps (\(p\) = 0.085, ES = 0.406). The peak ankle plantar flexor moment and angular impulse values were not different during any of the jumping phases, while the athletes increased their peak knee extension moment (\(p\) = 0.003, ES = 0.769) and angular impulse (\(p\) = 0.032, ES = 0.519) during the 21-40% phase.