From the Guidelines
Isokinetic contractions should be performed with a mixed isokinetic–isotonic programme to achieve better strength outcomes and reduce atrophy, as evidenced by the 2023 Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction 1. To safely and effectively perform isokinetic contractions, it is essential to follow proper guidelines.
- Begin by warming up for 5-10 minutes with light cardiovascular activity and dynamic stretching to increase blood flow to the muscles.
- Use specialized isokinetic equipment that controls movement speed while allowing maximal force production throughout the range of motion.
- Start with slower speeds (60-120 degrees per second) for strength development before progressing to faster speeds (180-300 degrees per second) for power and endurance.
- Perform 3-5 sets of 8-12 repetitions with 1-2 minutes rest between sets, gradually increasing resistance as strength improves, as supported by the finding that isotonic and isokinetic exercise significantly improved strength outcomes 1.
- Maintain proper body positioning and alignment during exercises, focusing on controlled movements and full range of motion.
- Include a 5-10 minute cool-down period with static stretching after your workout.
- Isokinetic training is effective because it accommodates resistance throughout the movement, maximizing muscle fiber recruitment and reducing injury risk by limiting force at weak points in the range of motion.
- Those with existing injuries or medical conditions should consult healthcare professionals before beginning an isokinetic training program, considering the benefits of isokinetic eccentric quadriceps training in improving isometric and eccentric strength at 3 months, as reported in the 2023 study 1.
From the Research
Guidelines for Safely and Effectively Performing Isokinetic Contractions
To perform isokinetic contractions safely and effectively, consider the following guidelines:
- Warm-up: Perform submaximal warm-ups prior to maximal testing to reduce the possibility of muscle strain 2.
- Proper Equipment: Use isokinetic dynamometers that can provide a record of applied force throughout a joint range of motion and control the speed of exercise at a predetermined rate 2, 3.
- Constant Velocity: Ensure that the angular velocity is held constant during the contraction, as this is a key characteristic of isokinetic contractions 2, 3.
- Force Measurement: Measure the force produced throughout the range of motion, taking into account the effects of gravity and inertial forces 2, 3.
- Muscle Analysis: Analyze the force-velocity curve of the muscle, recognizing that it may differ from the classic curve derived from prepared muscle specimens 2.
- Comparison of Contractions: When comparing different types of contractions, such as isotonic and isokinetic, control for total external work and mean angular movement velocity to ensure accurate comparisons 4.
- Training Programs: Consider using strategic strength resistance exercise programs to improve isokinetic muscular function, particularly for functional stability of the ankle joint 5.
- Cardiovascular Responses: Be aware of the potential cardiovascular responses to isokinetic exercise, including increases in heart rate and blood pressure, particularly in individuals with unrecognized cardiac diseases 6.
Key Considerations
When performing isokinetic contractions, keep in mind:
- The acceleration and deceleration periods of "isokinetic" exercise can limit the duration of the period of constant velocity 2.
- Impact artifacts on torque records can result from the compliance of the dynamometer system as it adjusts the accelerating limb to the present speed 2.
- The position at which peak torque occurs in a joint range varies with speed of motion 2.
- Neural inhibition of the force generated in intact muscle as tension rises has been postulated as a possible mechanism retarding the force curve at slow speeds 2.