Eccentric Exercise, Isokinetic Test
Conditions
Keywords
Eccentric exercise, Concentric exercise, oxygen consumption, muscle oxygenation
Brief summary
This study aims to measure and compare the metabolic response during sub maximal eccentric and concentric isokinetic exercise performed to exhaustion. Fourteen healthy female participants in the early phase of the menstrual cycle will perform concentric exercise with one lower limb and eccentric exercise with the contralateral limb. The assignment of exercise mode to limb and the order of testing will be randomized. The exercise protocol will consist of repeated knee extensor contractions on an isokinetic dynamometer for 10 minutes at 40% of maximal torque, followed by exercise at 70% of maximal torque until exhaustion. Oxygen consumption and respiratory quotient and will be measured continuously throughout exercise using open-circuit spirometry. Muscle oxygenation will be measured also continuously using near infrared spectroscopy. Lactate and pH concentration will be measured at frequent time points during the exercise to exhaustion.
Detailed description
The purpose of this study is to investigate and compare the metabolic responses during sub maximal eccentric and concentric isokinetic exercise performed to exhaustion. Eccentric and concentric muscle actions differ in their physiological and metabolic demands, but their effects on respiratory parameters during fatiguing isokinetic exercise are not fully understood. This study is designed to examine whether these two contraction modes produce distinct metabolic responses under controlled exercise conditions. Fourteen healthy female participants will be recruited and tested during the early phase of their menstrual cycle in order to reduce the possible influence of hormonal variation on physiological responses. A within-subject design will be used, with each participant completing both exercise conditions. One lower limb will perform concentric exercise and the contralateral lower limb will perform eccentric exercise. The limb allocation and the order of the two exercise conditions will be randomized. All exercise testing will be conducted on an isokinetic dynamometer. The protocol will involve repeated contractions of the knee extensor muscles. Each trial will begin with 10 minutes of exercise at 40% of maximal torque. Following this initial stage, the intensity will be increased to 70% of maximal torque and maintained until volitional exhaustion is reached. Oxygen consumption and respiratory quotient will be measured continuously throughout the exercise bout using open-circuit spirometry. Continuous monitoring of gas exchange during exercise will allow evaluation of substrate utilization and metabolic responses associated with each mode of contraction. Muscle oxygenation will be measured also continuously using near infrared spectroscopy. Lactate and pH concentration will be measured at frequent time points during the exercise to exhaustion. The study is expected to provide further insight into the metabolic and respiratory differences between eccentric and concentric exercise performed under submaximal but fatiguing isokinetic conditions. The findings may have implications for exercise testing, training prescription, and rehabilitation settings in which eccentric and concentric muscle actions are used for different physiological purposes.
Interventions
OTHERSub maximal concentric exercise
Based on their maximal performance on isokinetic concentric muscle contractions, participants performed sub-maximal concentric knee extensor exercise on an isokinetic dynamometer. The protocol consists of 10 minutes exercise at 40% of maximal torque followed by exercise at 70% of maximal torque until exhaustion. The exercise protocol was continuous, which mean that no interval was adopted at any stage of the protocol.
OTHERSub maximal eccentric exercise
Based on their maximal performance on isokinetic eccentric muscle contractions, participants performed sub-maximal concentric knee extensor exercise on an isokinetic dynamometer. The protocol consists of 10 minutes exercise at 40% of maximal torque followed by exercise at 70% of maximal torque until exhaustion. The exercise protocol was continuous, which mean that no interval was adopted at any stage of the protocol.
Sponsors
National and Kapodistrian University of Athens
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Each participant will complete both exercise conditions. One lower limb will perform concentric exercise and the contralateral lower limb will perform eccentric exercise. The limb allocation and the order of the two exercise conditions will be randomized.
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
* Physically active young females * No experience in activities involving significant resistance exercise components * No experience in muscle-damaging activities for at least 6-months prior to the study.
Exclusion criteria
* Any musculoskeletal injuries in the lower limbs within the past 6 months * Use of contraceptives * Irregular menstrual cycles * Smoking * Consumption of protein and antioxidant supplements * Potential inflammatory conditions.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Oxygen consumption | From the first intervention to the last intervention 2 weeks | Oxygen consumption will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise. |
| Muscle oxygenation | From the first intervention to the last intervention 2 weeks | Muscle oxygenation will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise. |
| Duration of the isokinetic exercise | From the first intervention to the last intervention 2 weeks | The whole duration of both isokinetic concentric and eccentric exercise will be recored |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Respiratory quotient | From the first intervention to the last intervention 2 weeks | Respiratory quotient will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise. |
| Lactate concentration | From the first intervention to the last intervention 2 weeks | Blood from fingertips will be collected periodically during the isokinetic exercise for both types of muscle contraction (concentric and eccentric) |
| pH measurement | From the first intervention to the last intervention 2 weeks | Blood will be collected periodically during the isokinetic exercise for both types of muscle contraction (concentric and eccentric) |
Countries
Greece
Outcome results
None listed