Pain assessment and possible mechanism of delayed onset muscle soreness

Muscle pain is felt during exercise or daily activities for several days after performing unaccustomed exercise, which is referred to as delayed onset muscle soreness (DOMS). Many people experience DOMS, but its underlying mechanisms are not fully understood. One of the challenges in the investigation of DOMS is its subjective nature, which makes the assessment ambiguous, thus establishing a standardised protocol is necessary. The present thesis scrutinised muscle pain assessments (Study 1, Study 2), developed a new assessment of muscle pain focusing on muscle fascia (Study 3), and investigated why DOMS is reduced after the second than the first bout of eccentric exercise (Study 4). From these studies, DOMS was thought to be more associated with connective tissue than muscle fibre damage and inflammation. In Study 1, the relationship between pain level assessed by a visual analogue scale (VAS) and pain sensitivity assessed by pressure pain threshold (PPT) was examined. Thirty-one healthy young men performed 10 sets of 6 maximal isokinetic eccentric contractions with their non-dominant arm. Before and 1 - 4 days after the exercise, muscle pain perceived upon palpation of the biceps brachii at three sites (5, 9, and 13 cm above the elbow crease) was assessed by VAS with a 100 mm line (0 = no pain, 100 = extremely painful), and PPT of the same sites was determined by an algometer. The VAS increased after exercise and peaked two days post-exercise, while the PPT decreased most at 1 day post-exercise and did not return to baseline for 4 days following exercise (P Muscle pain induced by elbow flexor eccentric exercise was investigated using different assessments in Study 2. Ten untrained men performed 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors with one arm. Maximal voluntary isometric contraction torque (MVC), range of motion (ROM) and serum creatine kinase (CK) activity were measured before, immediately after, and 1 to 5 days after exercise as indirect markers of muscle damage. PPT of 50 sites over an exercised upper arm, VAS with a 100-mm line for pain level upon static pressure by a cuff and fingers, and palpation of the biceps brachii at three sites (3, 9, and 15 cm above the elbow crease) and different palpation methods (longitudinal, transverse and circular movements) on the mid-belly of biceps were assessed. Large decreases in MVC and ROM, and significant increases in serum CK activity indicated muscle damage. A significant difference (P In Study 3, changes in the electrical pain threshold (EPT) of the biceps brachii fascia, biceps brachii muscle and brachialis fascia following eccentric elbow flexor contractions, and the relationship between EPT and VAS or PPT were investigated. Ten healthy untrained men performed two eccentric exercise bouts (ECC1, ECC2) consisting of 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors with the same arm separated by 4 weeks. Changes in MVC, ROM, VAS and PPT were smaller (P The purpose of Study 4 was to investigate the magnitude of muscle lengthening during the first and second bout of eccentric exercise bouts and whether the muscle length changes are associated with the magnitude of DOMS and changes in other indirect markers of muscle damages between bouts. Ten healthy untrained men performed two eccentric exercise bouts (ECC1, ECC2) consisting of 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors using the same arm separated by 4 weeks. Changes in MVC, ROM, muscle thickness, ultrasound echo intensity, serum CK activity and muscle soreness (VAS) were smaller (P

Grantor dc:publisher

Edith Cowan University, Research Online, Perth, Western Australia

Year dc:date

2014

Author dc:creator

• Lau, Wing Yin

• Eccentric exercise
• Delayed onset muscle soreness
• VAS
• PPT
• EPT
• Muscle lengthening
• Muscle damage
• Muscles - Metabolism
• Muscles - Physiology
• Muscles - Wounds and injuries
• Exercise - Physiological aspects
• Exercise Physiology
• Musculoskeletal System
• Sports Sciences

Repository record dc:identifier

https://ro.ecu.edu.au/theses/1275

OAI identifier oai:identifier

oai:ro.ecu.edu.au:theses-2276