Neuromuscular and perceptual responses to moderate-intensity incline, level and decline treadmill exercise.
PURPOSE
To describe the neuromuscular and perceptual responses to incline, decline or level treadmill exercise.


METHODS
Fifteen healthy subjects performed on separate days 45 min treadmill exercise at 75% heart rate reserve in a level (+ 1% slope), incline (+ 15%) or decline condition (- 15%). Neuromuscular function of the knee extensors (KE) was assessed before and after exercise. Perception of effort, muscle pain and pleasure were measured during the exercise. Muscle pain was also reported up to 96 h after exercise.


RESULTS
At the same heart rate, the decline exercise was performed at a higher velocity. This higher velocity was associated with a higher perceived effort and muscle pain, as well as lower pleasure. Maximal isometric KE peak torque and maximal voluntary activation similarly decreased in the three conditions (~ 15 ± 12 and ~ 4 ± 4%). M-wave amplitude of the vastus medialis muscle decreased in the three conditions (~ - 12 ± 13%). M-wave amplitude of the rectus femoris muscle decreased only after the decline exercise (- 12 ± 16%). Peak twitch torque of the electrically evoked contractions was reduced after incline and decline exercises for both 10 and 100 Hz doublets (- 8 ± 9 and - 17 ± 18%). The Dt10/Dt100 ratio was reduced only after decline exercise (- 24 ± 19%).


CONCLUSION
At the same moderate intensity, decline exercise induced a greater level of muscle fatigue associated with a higher perceived effort and muscle pain than incline and level exercise. Exercise intensity should be carefully monitored during decline locomotion for training or rehabilitation purposes.
['Garnier|Yoann M|YM|http://orcid.org/0000-0001-5778-4684', 'Lepers|Romuald|R|http://orcid.org/0000-0002-3870-4017', 'Dubau|Quentin|Q|', 'Pageaux|Benjamin|B|http://orcid.org/0000-0001-9302-5183', 'Paizis|Christos|C|http://orcid.org/0000-0002-5070-7915']
D000328:Adult D004558:Electric Stimulation D004576:Electromyography D015444:Exercise D005080:Exercise Test D006339:Heart Rate D006801:Humans D007717:Knee D007719:Knee Joint D008297:Male D009119:Muscle Contraction D018763:Muscle Fatigue D018482:Muscle, Skeletal D063806:Myalgia D019415:Torque
Muscle pain Muscle fatigue Concentric Eccentric Rating of perceived exertion Running