Acute Muscle Damage Responses in Elbow Flexors Following Eccentric Quasi-isometric Exercise
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 30
- 试验地点
- 1
- 主要终点
- Maximal Voluntary Isometric Contraction (MVC) Torque
研究概览
简要总结
This study compared the acute muscle damage responses of the elbow flexor muscles following two types of resistance exercise: eccentric quasi-isometric (EQI) exercise and traditional eccentric (ECC) exercise. Thirty healthy young men were randomly assigned to perform either EQI or ECC using a dumbbell elbow flexion exercise. Both groups exercised with the same relative external load and performed the exercise to voluntary fatigue.
Muscle function, muscle soreness, and blood markers related to muscle damage were assessed before exercise, immediately after exercise, and over a 7-day recovery period. The purpose of this study was to examine whether EQI exercise, which involves a prolonged isometric phase followed by a very slow eccentric action, induces different levels of acute muscle damage and recovery compared with traditional eccentric exercise.
详细描述
Eccentric resistance exercise is widely used in strength training but is often associated with substantial exercise-induced muscle damage, resulting in strength loss, muscle soreness, swelling, and prolonged recovery. Eccentric quasi-isometric (EQI) exercise is a recently proposed contraction mode that combines a sustained isometric hold with a subsequent extremely slow eccentric lengthening under continuous voluntary resistance. This contraction pattern results in prolonged time under tension while avoiding rapid lengthening or abrupt force spikes.
In this randomized interventional study, thirty healthy young men with no recent resistance training experience were randomly assigned to perform either EQI or traditional eccentric (ECC) exercise of the elbow flexors. Participants performed unilateral dumbbell elbow flexion exercise at 70% of their one-repetition maximum. The EQI group completed five sets of single repetitions consisting of an initial isometric hold at 90 degrees of elbow flexion until task failure, followed by very slow eccentric lengthening to full elbow extension. The ECC group performed five sets of repeated eccentric-only elbow flexion exercises at a controlled tempo until failure. Rest intervals were standardized between sets.
Muscle damage and recovery were evaluated using multiple functional and biochemical indicators, including maximal voluntary isometric contraction torque, elbow joint range of motion, upper arm circumference, pressure pain threshold, and circulating concentrations of creatine kinase and myoglobin. Measurements were obtained before exercise, immediately after exercise, and at 1, 2, 3, and 7 days following the exercise bout.
The primary objective of this study was to compare the acute muscle damage responses and recovery profiles of the elbow flexors following EQI and ECC exercise when performed to voluntary fatigue at the same relative external load.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 20 Years 至 30 Years（Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •Healthy young men
- •Age between 20 and 30 years
- •No participation in any regular exercise training programs during the previous 12 months
- •No history of cardiovascular disease, diabetes mellitus, liver disease, respiratory disorders, neuromuscular disease, or musculoskeletal disorders
- •No long-term use of chronic prescription medications
- •No history of dizziness, chest discomfort, or falls during physical activity
- •Not previously diagnosed by a physician as unsuitable for exercise
排除标准
- •History of upper limb musculoskeletal, joint, or bone injuries
- •Inability to independently perform activities of daily living
- •Presence of cardiovascular, metabolic, respiratory, neuromuscular, or musculoskeletal disorders
- •Requirement for assistive devices for ambulation in daily life
- •Previous medical diagnosis indicating unsuitability for exercise participation
- •Presence of acute illness at the time of enrollment
- •History of major surgery within the past 12 months
- •Severe physical injury that could impair exercise performance or daily activities
研究组 & 干预措施
eccentric quasi-isometric (EQI)
Participants assigned to this arm performed eccentric quasi-isometric (EQI) exercise of the elbow flexors using a unilateral dumbbell preacher curl. The external load was set at 70% of each participant's one-repetition maximum. Each repetition began with a sustained isometric hold at 90 degrees of elbow flexion until task failure, followed immediately by a very slow eccentric lengthening to full elbow extension while participants continued to resist the load. Participants completed five sets of one repetition, with 90 seconds of rest between sets. All repetitions were performed to voluntary fatigue under supervision.
干预措施: Eccentric Quasi-Isometric Exercise (Behavioral)
Traditional Eccentric Exercise (ECC)
Participants assigned to this arm performed traditional eccentric-only exercise of the elbow flexors using a unilateral dumbbell preacher curl. The external load was set at 70% of each participant's one-repetition maximum. From a starting position of 90 degrees of elbow flexion, participants repeatedly lowered the dumbbell through the full range of motion using controlled eccentric contractions at a cadence of approximately 2.5 seconds per repetition, guided by a metronome. Each set was performed to voluntary failure, and a total of five sets were completed with 90 seconds of rest between sets.
干预措施: Traditional Eccentric Exercise (Behavioral)
结局指标
主要结局
Maximal Voluntary Isometric Contraction (MVC) Torque
时间窗: Baseline (Day 0) and Days 1, 2, 3, and 7
Maximal voluntary isometric contraction (MVC) torque of the elbow flexors was assessed using an isokinetic dynamometer with the elbow positioned at 90 degrees of flexion. Participants performed three maximal 3-second isometric contractions with standardized verbal encouragement. The highest torque value obtained across trials was used for analysis as an indicator of muscle function and strength loss following exercise.
次要结局
- Elbow Joint Range of Motion (ROM)(Baseline (Day 0) and Days 1, 2, 3, and 7)
- Upper Arm Circumference (CIR)(Baseline (Day 0) and Days 1, 2, 3, and 7)
- Pressure Pain Threshold (PPT)(Baseline (Day 0) and Days 1, 2, 3, and 7)
- Plasma Creatine Kinase (CK)(Baseline (Day 0) and Days 1, 2, 3, and 7)
- Plasma Myoglobin (Mb)(Baseline (Day 0) and Days 1, 2, 3, and 7)
- Time Under Tension (TUT)(Day 1)
研究者
TSUNG-LIN CHIANG
Principal Investigator
Chinese Culture University