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D L MacIntyre

Publications and source records attributed to D L MacIntyre.

7 recordsLinked to original sources
PubMed2001

Markers of inflammation and myofibrillar proteins following eccentric exercise in humans.

The purpose of this study was to examine the time-course and relationships of technetium-99m (99mTc) neutrophils in muscle, interleukin-6 (IL-6), myosin heavy chain fragments (MHC), eccentric torque, and delayed onset muscle soreness (DOMS) following eccentric exercise in humans. Twelve male subjects completed a pre-test DOMS questionnaire, performed a strength test and had 100 ml blood withdrawn for analysis of plasma IL-6 and MHC content. The neutrophils were separated, labelled with 99mTc, and re-infused into the subjects immediately before the exercise. Following 300 eccentric repetitions of the right quadriceps muscles on an isokinetic dynamometer, the subjects had 10 ml of blood withdrawn with repeated the eccentric torque exercise tests and DOMS questionnaire at 0, 2, 4, 6, 20, 24, 48, 72 h, and 6 and 9 days. Bilateral images of the quadriceps muscles were taken at 2, 4, and 6 h. Computer analysis of regions of interest was used to determine the average count per pixel. The 99mTc neutrophils and IL-6 increased up to 6 h post-exercise (P < 0.05). The neutrophils were greater in the exercised muscle than the non-exercised muscle (P < 0.01). The DOMS was increased from 0 to 48 h, eccentric torque decreased from 2 to 24 h, and MHC peaked at 72 h post-exercise (P < 0.001). Significant relationships were found between IL-6 and 2 h and DOMS at 24 h post-exercise (r = 0.68) and assessment of the magnitude of change between IL-6 and MHC (r = 0.66). These findings suggest a relationship between damage to the contractile proteins and inflammation, and that DOMS is associated with inflammation but not with muscle damage.

Adult↗
PubMed2000

Different effects of strenuous eccentric exercise on the accumulation of neutrophils in muscle in women and men.

The purpose of this study was to evaluate the sex differences in delayed onset muscle soreness (DOMS), torque, and accumulation of technetium-99m (Tc-99m) neutrophils in eccentric-exercised muscle. A group of 10 female and 12 male subjects took part in this study. The subjects completed a pre-test using the descriptor differential scale (DDS) to describe DOMS, and tests of concentric and eccentric torque of the right quadriceps. A volume of 100 ml of blood was taken by venipuncture for neutrophil labelling in the early morning of the exercise day. The Tc-99m neutrophils were re-infused intravenously before the eccentric exercise. The exercise stimulus consisted of 300 eccentric repetitions of the right quadriceps muscles. Radionuclide images of both quadriceps muscles (lateral views) were taken at 2 and 4 h. The DDS, and concentric and eccentric torques of the quadriceps were subsequently evaluated at 0 h, 2, 4, 20 and 24 h post-exercise. The presence of Tc-99m neutrophils was greater in the exercised leg than the non-exercised leg at 2 and 4 h post-exercise (P </= 0.013) and greater in the exercised leg of the women compared to the men at 2 h (P = 0.03). The DOMS had increased post-exercise (P < 0.001) and torque had decreased post-exercise (P </= 0.002) but the patterns were different between the sexes. We concluded that the sex influences the presence of Tc-99m neutrophils in the exercised muscle following eccentric exercise. In addition, different patterns of DOMS and torque were observed between the sexes after eccentric exercise, and require further investigation.

Adult↗
PubMed1996

Presence of WBC, decreased strength, and delayed soreness in muscle after eccentric exercise.

The purposes of this study were to assess the presence of 99mTc-labeled white blood cells (WBC) in exercised muscle compared with nonexercised muscle over time and to determine the time course of delayed onset muscle soreness (DOMS) and eccentric torque in 10 female subjects. A pretest was followed by 300 eccentric repetitions of the right quadriceps. DOMS and eccentric torque were measured at 2, 4, 20, 24, 48, and 72 h postexercise. Eccentric torque was also tested at 0 h. Radionuclide images of both quadriceps were taken at 2, 4, 20, and 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle was significantly greater (P < 0.001) than in the nonexercised muscle. Eccentric torque declined at 0 and 24 h postexercise. DOMS peaked at 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle in the first 24 h suggests that acute inflammation occurs as a result of exercise-induced muscle injury. The bimodal pattern of eccentric torque supports the hypothesis that more than one mechanism is involved.

Adult↗
PubMed1995

Delayed muscle soreness. The inflammatory response to muscle injury and its clinical implications.

Delayed onset muscle soreness (DOMS) is a sensation of discomfort that occurs 1 to 2 days after exercise. The soreness has been reported to be most evident at the muscle/tendon junction initially, and then spreading throughout the muscle. The muscle activity which causes the most soreness and injury to the muscle is eccentric activity. The injury to the muscle has been well described but the mechanism underlying the injury is not fully understood. Some recent studies have focused on the role of the cytoskeleton and its contribution to the sarcomere injury. Although little has been confirmed regarding the mechanisms involved in the production of delayed muscle soreness, it has been suggested that the soreness may occur as a result of mechanical factors or it may be biochemical in nature. To date, there appears to be no relationship between the development of soreness and the loss of muscle strength, in that the timing of the two events is different. Loss of muscle force has been observed immediately after the exercise. However, by collecting data at more frequent intervals a second loss of force has been reported in mice 1 to 3 days post-exercise. Future studies with humans may find this second loss of force to be related to DOMS. The role of inflammation during exercise-induced muscle injury has not been clearly defined. It is possible that the inflammatory response may be responsible for initiating, amplifying, and/or resolving skeletal muscle injury. Evidence from the literature of the involvement of cytokines, complement, neutrophils, monocytes and macrophages in the acute phase response are presented in this review. Clinically, DOMS is a common but self-limiting condition that usually requires no treatment. Most exercise enthusiasts are familiar with its symptoms. However, where a muscle has been immobilised or debilitated, it is not known how that muscle will respond to exercise, especially eccentric activity.

Cytokines↗
PubMed1992

Quadriceps muscle activity in women runners with and without patellofemoral pain syndrome.

The purpose of this study was to determine whether there was a difference in the electromyographic (EMG) patterns of the quadriceps muscles in women runners diagnosed with patellofemoral pain syndrome (PFPS) compared to the quadriceps activity of women runners free of knee pain and with normal lower extremity alignment. Linear envelope EMGs from vastus medialis, vastus lateralis, and rectus femoris, together with a footswitch signal, were recorded as each subject ran on a treadmill at 80% of their normal running pace and at 12km/h. Each stride period was normalized to 100%, then the linear envelopes for ten trials were ensemble averaged to achieve a mean ensemble for each muscle from each subject. Subsequently, the ensembles for each subject were normalized by dividing by the maximum EMG per cycle; they were then averaged across subjects to obtain the grand mean ensembles of each muscle for each group. Comparisons between the experimental and control groups at both speeds showed that nowhere during the stride cycle did the mean EMG levels of the two groups differ by more than two standard deviations. It was concluded that any changes in the running pattern of the runners with patellofemoral pain syndrome could not be detected by changes in the EMG patterns.

Adult↗
PubMedDate not supplied

Fatigue of the knee extensor muscles following eccentric exercise.

The purposes of this study were to determine the time course of muscle fatigue in the knee extensor muscles following an eccentric exercise protocol, and to determine if the position of the subjects during assessment affected the measurement of muscle fatigue. Twenty-four female subjects were assigned to three groups. All subjects completed baseline measure (pre-exercise test) of a power spectrum analysis of the vastus medialis, rectus femoris and vastus lateralis muscles. Following an exercise protocol of 300 eccentric repetitions of the knee extensors, power spectrum analysis was repeated at two, four, 20, 24, 48 and 72 hours for group one, at 0 hour (immediately following the exercise) and two hours for group two, and at 0 hour for group three. Groups one and two were tested in sitting, while group three was tested supine. The slope of the median frequency of the vastus lateralis muscle changed significantly over time (p < 0.001) for group one, but there were no significant changes in the slope of the median frequency of the vastus medialis muscle, while the rectus femoris muscle showed an increase in the slope of the median frequency when the subjects were in the sitting position. Further testing, in supine (group three), indicated that the position of the hip joint influenced the power spectrum analysis of the rectus femoris muscle but not the vasti muscles. In addition, fatigue occurred immediately post-exercise with recovery within 24 hours.

Adult↗