Related Experiment Video
Updated: Jun 23, 2026
07:22
Measuring the Motor Aspect of Cancer-Related Fatigue using a Handheld Dynamometer
Published on: February 20, 2020
Neuromuscular fatigue after resistance training
M Izquierdo1, J Ibañez, J A L Calbet
1Studies, Research and Sport Medicine Center, Government of Navarre, Spain. mikel.izquierdo@ceimd.org
International Journal of Sports Medicine
|April 22, 2009
Summary
Heavy resistance training increases exercise-induced fatigue. Post-training, muscles can perform more work and accumulate metabolites, leading to faster and more profound strength loss during dynamic fatiguing exercise.
Area of Science:
- Exercise Physiology
- Sports Science
- Muscle Physiology
Background:
- Heavy resistance training enhances maximal strength and muscle power.
- Understanding exercise-induced fatigue is crucial for optimizing training protocols.
- The impact of training on fatigue development under different loading conditions requires further investigation.
Purpose of the Study:
- To investigate the effects of heavy resistance training on dynamic exercise-induced fatigue.
- To compare fatigue development under protocols of same relative intensity (5 x 10RM(Rel)) and same absolute load (5 x 10RM(Abs)).
- To analyze changes in maximal strength, muscle power, electromyography (EMG) signals, and metabolic responses post-training.
Main Methods:
- Twelve men underwent a heavy resistance training program.
- Measurements included maximal strength, muscle power, surface EMG (amplitude and spectral indices), blood lactate, and ammonia concentrations.
- Exercise-induced fatigue was assessed using a 5 x 10RM leg-press task before and after training under two loading protocols (relative and absolute intensity).
Main Results:
- After training, greater exercise-induced loss in maximal strength was observed when relative intensity was maintained (5 x 10RM(Rel)).
- Peak power loss was significantly higher in the 5 x 10RM(Rel) protocol (58-62%) compared to isometric strength decline (12-17%).
- Similar neural adjustments were noted, but higher accumulated fatigue and metabolic demand occurred with 5 x 10RM(Rel).
Conclusions:
- Heavy resistance training allows muscles to perform more work and accumulate more metabolites before task failure.
- Despite similar EMG changes, the rate of fatigue development (power and MVC loss) was faster and more profound post-training under the same relative intensity.
- These findings highlight the complex interplay between training adaptations, loading conditions, and fatigue development during dynamic exercise.
Related Concept Videos
01:24Muscle Recovery and Fatigue
Muscle fatigue refers to the decline in a muscle's ability to maintain the force of contraction after prolonged activity. It primarily stems from changes within muscle fibers. Even before experiencing muscle fatigue, one may feel tired and have the urge to stop the activity. This response, known as central fatigue, occurs due to changes in the central nervous system, namely the brain and spinal cord. While there is no single mechanism that induces fatigue, it may serve as a protective response...
01:27Exercise and Muscle Performance
Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
01:25Energy Supply for Muscle Contraction
Skeletal muscle fibers have the unique ability to switch between rest and contraction states, using different sources of ATP for energy. The contraction cycle and Ca2+ transport back into the sarcoplasmic reticulum for relaxation require significant ATP. However, the ATP reserves in muscle fibers are limited and can only sustain contractions for a few seconds. Additional ATP production becomes necessary for prolonged contractions. As a result, muscle fibers generate ATP through various sources,...
01:29Relaxation of Skeletal Muscles
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
01:21Fatigue
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
01:22Myasthenia Gravis ll: Pathophysiology
The disease process of myasthenia gravis begins at the neuromuscular junction, where antibodies attack key proteins needed for muscle activation. This immune reaction weakens signal transmission, leading to the characteristic muscle fatigue and weakness that define the condition.Immune-Mediated DamageIn most individuals, antibodies target acetylcholine receptors (AChRs) on the postsynaptic membrane of muscle cells. By blocking acetylcholine binding, these antibodies prevent the nerve signal...