Biomedical subjects

Mike Newton

Publications and source records attributed to Mike Newton.

5 recordsLinked to original sources

PubMed2002

Delayed-onset muscle soreness does not reflect the magnitude of eccentric exercise-induced muscle damage.

This study investigated the relationship between delayed-onset muscle soreness and other indicators of muscle damage following eccentric exercise. Male students (n = 110) performed 12 (12ECC), 24 (24ECC), or 60 maximal eccentric actions of the elbow flexors (60ECC). Maximal isometric force, relaxed and flexed elbow joint angles, upper arm circumference, and plasma creatine kinase activity were assessed immediately before and after, and for 4 days after exercise. Muscle soreness (SOR) was evaluated by a visual analog scale (a 50-mm line, 0: no pain, 50: extremely painful) when the elbow flexors were palpated (SOR-Pal), flexed (SOR-Flx) and stretched (SOR-Ext). Although 24ECC and 60ECC resulted in significantly (P <; 0.05) larger changes in all indicators and slower recovery compared to 12ECC, no significant differences were evident for SOR-Pal and SOR-Flx between 12ECC and 24ECC, or 12ECC and 60ECC. In contrast, SOR-Ext was significantly (P <; 0.05) lower for 12ECC compared to 24ECC and 60ECC. A Pearson product-moment correlation showed SOR-Pal did not correlate significantly with any indicators, however, SOR-Ext and SOR-Flx showed weak (r <; 0.32) but significant (P <; 0.05) correlations with other indicators. Because of generally poor correlations between DOMS and other indicators, we conclude that use of DOMS is a poor reflector of eccentric exercise-induced muscle damage and inflammation, and changes in indirect markers of muscle damage and inflammation are not necessarily accompanied with DOMS.

Adult↗

PubMed2002

Concentric or eccentric training effect on eccentric exercise-induced muscle damage.

PURPOSE: The purpose of this study was to compare changes in muscle damage indicators following 24 maximal eccentric actions of the elbow flexors (Max-ECC) between the arms that had been previously trained either eccentrically or concentrically for 8 wk. METHODS: Fifteen subjects performed three sets of 10 repetitions of eccentric training (ECC-T) with one arm and concentric training (CON-T) with the other arm once a week for 8 wk using a dumbbell representing 50% of maximal isometric force of the elbow flexors (MIF) determined at the elbow joint of 90 degrees (1.57 rad). The dumbbell was lowered from a flexed (50 degrees, 0.87 rad) to an extended elbow position (180 degrees, 3.14 rad) in 3 s for ECC-T, and lifted from the extended to the flexed position in 3 s for CON-T. Max-ECC was performed 4 wk after CON-T and 6 wk after ECC-T. Changes in MIF, range of motion (ROM), upper arm circumference (CIR), muscle soreness (SOR), and plasma creatine kinase (CK) activity were compared between the ECC-T and CON-T arms. RESULTS: The first ECC-T session produced larger decreases in MIF and ROM, and larger increases in CIR and SOR compared with CON-T. CK increased significantly (P < 0.01) and peaked 4 d after the first training session, but did not increase in the following sessions. All measures changed significantly (P < 0.01) following Max-ECC; however, the changes were not significantly different between ECC-T and CON-T arms. CONCLUSION: These results showed that ECC-T did not mitigate the magnitude of muscle damage more than CON-T, and CON-T did not exacerbate muscle damage.

Adaptation, Physiological↗

PubMed2002

Muscle damage and soreness after endurance exercise of the elbow flexors.

PURPOSE: This study investigated changes in indirect markers of muscle damage after endurance exercise of the elbow flexors and compared the changes with those after maximal eccentric actions (Max-ECC) of the elbow flexors. METHODS: Eighteen male students rhythmically lifted (1 s) and lowered (1 s) a light dumbbell (1.1-1.8 kg: 9% of MIF) in 60-180 degrees of elbow joint angle for 2 h (2-h Ex). Maximal isometric force (MIF), relaxed (RANG) and flexed elbow joint angles (FANG), upper-arm circumference (CIR), muscle soreness (SOR), B-mode ultrasound (US), and plasma creatine kinase (CK) activity were assessed before and immediately after, and up to 96 h after exercise. RESULTS: All measures were altered significantly (P < 0.05) after 2-h Ex in a similar time course to Max-ECC; however, changes in RANG, FANG, CIR, US, and CK (peak: 356 +/- 121 IU.L-1) were significantly (P < 0.05) smaller compared with those after Max-ECC. SOR developed immediately after 2-h Ex and peaked 24-48 h after exercise. MIF dropped to 44.1% of the preexercise level, which was significantly (P < 0.05) lower than that after Max-ECC (58.1%), immediately postexercise. MIF recovered to 79.8% at 24 h, and 97.8% at 96 h postexercise, which was a significantly (P < 0.05) faster recovery compared with that of Max-ECC (73.1% at 96 h). CONCLUSION: These results showed low-intensity continuous muscle contractions (3600 times) resulted in muscle damage; however, the magnitude of the muscle damage was less severe, and the recovery was faster compared with 12 maximal eccentric muscle actions.

Adolescent↗

PubMed2002

Repeated eccentric exercise bouts do not exacerbate muscle damage and repair.

This study examined whether performing repeated bouts of eccentric exercise 2 and 4 days after an initial damaging bout would exacerbate muscle damage. One arm performed 3 sets of 10 eccentric actions of the elbow flexors (ECC1) using a dumbbell set at 50% of the maximal isometric force at 90 degrees (SINGLE). Two weeks later the same exercise was performed by the opposite arm with the exception that subsequent bouts were performed 2 (ECC2) and 4 (ECC3) days after ECC1 (REPEATED). In the REPEATED condition, maximal isometric force (MIF) decreased to the same level immediately after ECC1-3, and the decreases in range of motion (ROM) and increases in upper arm circumference immediately postexercise were similar among the bouts. However, no significant differences in changes in MIF, ROM, muscle soreness, and plasma creatine kinase activity were evident between the SINGLE and REPEATED conditions when excluding the changes immediately after ECC2 and ECC3. These results suggest that ECC2 and ECC3 did not exacerbate muscle damage or affect the recovery process.

Adolescent↗

PubMed2002

Difference in the magnitude of muscle damage between maximal and submaximal eccentric loading.

This study compared maximal (MAX-ECC) and submaximal (50%-ECC) eccentric exercise of the elbow flexors. Untrained male students (n = 8) performed 3 sets of 10 repetitions of MAX-ECC with one arm and 50%-ECC with the other arm, separated by 4 weeks. In MAX-ECC, the elbow joint was forcibly extended from a flexed (90 degrees ) to a full-extended position (180 degrees ) in 3 seconds while producing maximal force. For 50%-ECC, a dumbbell set at 50% of the maximal isometric strength at 90 degrees of the elbow joint was lowered from the flexed to the extended position in 3 seconds. Changes in indicators of muscle damage were compared between the bouts by a 2-way repeated-measures analysis of variance. Changes in isometric strength, range of motion, upper arm circumference, and plasma creatine kinase activity were significantly smaller and the recovery was significantly faster for 50%-ECC compared with MAX-ECC, although the differences in the changes immediately after exercise were small. It appeared that the magnitude of initial muscle damage was similar between the bouts; however, secondary damage was less after 50%-ECC.

Adolescent↗