Donna L. MacIntyre

Markers of inflammation and myofibrillar proteins following eccentric exercise in humans

Abstract 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 Twelve male subjects completed a pre-test DOMS questionnaire, performed a strength test and had 100 ml blood withdrawn for analysis of plasma IL-6 and MHC content.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300 eccentric repetitions of the right quadriceps muscles on an isokinetic dynamometer, the subjects had 10 ml of blood withdrawn and repeated the eccentric torque exercise tests and DOMS questionnaire at 0, 2, 4, 6, 20, 24, 48, 72 h, and 6 and 9 days.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 at 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.

Leg muscle strength is reduced in Parkinson's disease and relates to the ability to rise from a chair

Individuals with Parkinsons disease (PD) have difficulties rising from a chair; however, factors contributing to this inability have never been investigated. We compared lower extremity strength between individuals with PD and healthy controls and quantified the relationships between strength and the ability to rise from a chair. Ten men with mild PD and 10 sex‐ and age‐matched controls performed maximal concentric, isokinetic knee and hip extensor torque on an isokinetic dynamometer to quantify muscle strength. Subjects also rose from a chair at their comfortable pace without the use of their arms and the duration of this task provided a measure of sit‐to‐stand (STS) ability. Subjects with PD were tested in an on‐ and off‐medication state on different days. Mean hip and knee extensor torques were lower in subjects with PD, with greater deficits found at the hip. Greater hip strength was related to better STS ability in subjects with PD while greater knee strength was related to better STS ability in controls. These results show that individuals with mild PD generate smaller extremity forces compared to controls. Reduced strength, particularly at the hip, may be one factor that contributes to the difficulty of persons with PD to rise from a chair.

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

Abstract 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.

Effects of Pilates Exercises on Shoulder Range of Motion, Pain, Mood, and Upper-Extremity Function in Women Living With Breast Cancer: A Pilot Study

Background and Purpose: The purpose of this study was to examine the effects of Pilates exercises on shoulder range of motion (ROM), pain, mood, and upper-extremity (UE) function in women who had been treated for breast cancer. Participants: The participants were 4 women who had undergone axillary dissection and radiation therapy for stage I to IV breast cancer. Methods: A nonconcurrent, multiple-baseline, single-subject research design was used to examine the effects of Pilates exercises on the 4 outcomes. Results: Visual analyses of the data suggest a modest effect of the Pilates exercise program in improving shoulder abduction and external rotation ROM. Statistically significant improvement in shoulder internal and external rotation in the affected UE was shown for the one participant with pre-existing metastatic disease. The improving baselines seen for pain, mood, and UE function data made it impossible to assess the effects of Pilates exercises on those outcomes. No adverse events were experienced. Discussion and Conclusion: Pilates exercises may be an effective and safe exercise option for women who are recovering from breast cancer treatments; however, further research is needed.

Falls in people with chronic obstructive pulmonary disease: an observational cohort study

STUDY OBJECTIVE To investigate incidence, risk factors and impact of falls on health related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD). DESIGN Observational cohort study. METHODS Patients completed these questionnaires at baseline and at 6-months: Medical Outcomes Study Short Form 36 (SF-36), Chronic Respiratory Questionnaire (CRQ), Activities Balance Confidence (ABC) Scale and a form to record demographic data, medications, co-morbidities, oxygen use, acute exacerbations, fall history and assistive device use. Physical activity was measured with the Physical Activity Scale for the Elderly (PASE) only at baseline. Fall incidence was monitored through monthly fall diaries. Patients were categorized as non-fallers (0 falls) or fallers (≥ 1 falls). RESULTS Data from 101 patients with a forced expiratory volume in 1 s of 46.4 ± 21.6% predicted were analyzed. Thirty-two patients (31.7%) reported at least one fall during the 6-months. Fall incidence rate was 0.1 (95% CI: 0.06-0.14) falls per person-month. Fallers tended to be older (p = 0.04), female (p = 0.04) and oxygen dependent (p = 0.02), have a history of previous falls (p < 0.001), more co-morbidities (p = 0.007) and take more medications (p = 0.001). Previous falls (OR = 7.36; 95% CI: 2.39-22.69) and diagnosis of coronary heart disease (OR = 7.07; 95% CI: 2.14-23.36) were the most important predictors of falls. The Dyspnea Domain of the CRQ declined significantly more (p = 0.02) in the fallers group at 6-months. CONCLUSIONS Patients with COPD have a high susceptibility to falls, which is associated with a worsening of dyspnea perception as related to HRQoL. Fall prevention programs in COPD are recommended.

Preservation of eccentric strength in older adults: Evidence, mechanisms and implications for training and rehabilitation

Overall reductions in muscle strength typically accompany the aging process. However, older adults show a relatively preserved capacity of producing eccentric strength. The preservation of eccentric strength in older adults is a well-established phenomenon, occurring indiscriminately across different muscle groups, independent of age-related architectural changes in muscle structure and velocity of movement. The mechanisms for the preservation of eccentric strength appear to be mechanical and cellular in origin and include both passive and active elements regulating muscle stiffness. The age-related accumulation of non-contractile material in the muscle-tendon unit increases passive stiffness, which might offer mechanical advantage during eccentric contractions. In addition, the preserved muscle tension and increased instantaneous stiffness of old muscle fibers during stretch increase active stiffness, which might enhance eccentric strength. The fact that the preservation of eccentric strength is present in people with chronic conditions when compared to age-matched healthy controls indicates that the aging process per se does not exclusively mediate the preservation of eccentric strength. Physical inactivity, which is common in elderly and people with chronic conditions, is a potential factor regulating the preservation of eccentric strength. When compared to concentric strength, the magnitude of preservation of eccentric strength in older adults ranges from 2% to 48% with a mean value of 21.6% from all studies. This functional reserve of eccentric strength might be clinically relevant, especially to initiate resistance training and rehabilitation programs in individuals with low levels of strength.

Test-retest reliability of glenohumeral internal and external rotator strength.

ObjectiveTo establish test-retest reliability for a strength testing protocol of the glenohumeral internal and external rotator muscles using a KinCom (Chattanooga Group, Hixson, TN) isokinetic dynamometer. DesignProspective test-retest reliability study. SettingRehabilitation research laboratory. ParticipantsFourteen volunteers between the ages of 27 and 35 years participated in the study. Subjects had no history of traumatic shoulder injury and no overuse-based shoulder pain interfering with activity within the last 6 months. Nine of the 14 subjects were not participating in more than 6 hours weekly of arm-based sporting activities, while the remaining five subjects were involved in swim training at workout volumes of no greater than 3000 m per week. InterventionSubjects performed three test sessions of four maximal repetitions each of concentric and eccentric shoulder internal and external rotation bilaterally in a standardized sitting position. An average of 5.9 days occurred between consecutive test sessions (range, 2–21 days). Main Outcome MeasuresAverage torque data were collected for concentric and eccentric internal and external rotation tests bilaterally. Intraclass correlation coefficients were calculated to compare the data across sessions. Pearson product moment correlation coefficients were calculated to assess reliability between sessions. ResultsHigh test-retest reliability, ranging from 0.82 to 0.97, was demonstrated for all tests. ConclusionsThe results indicate that a reliable test protocol has been determined for shoulder internal and external rotation strength testing on the KinCom isokinetic dynamometer.

Deficits in muscle strength, mass, quality, and mobility in people with chronic obstructive pulmonary disease

PURPOSE Midthigh intramuscular fat (IF), a feature of reduced muscle quality, is an important predictor of self-reported mobility loss in the elderly. This study compared measures of muscle strength, mass, IF, and mobility in patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. Associations between measures of muscle strength, mass, IF, and mobility were explored. METHODS Knee extensor muscle strength was assessed with an isokinetic dynamometer. Cross-sectional area and IF of the thigh muscles were measured with computerized tomography. Mobility was assessed with the repetitive sit-to-stand, self-selected gait speed, and 6-minute walk tests. RESULTS Patients with COPD (n = 21, age 71.3 ± 8.1 years, and a percentage predicted force expiratory volume in 1 second of 47.2 ± 12.9) and 21 healthy subjects matched for age (67.4 ± 8.6 years), gender, and body mass participated in the study. Patients with COPD showed reduced average knee extensor strength (29%, P = .016) cross-sectional area of the thigh muscles (17%, P = .007) and mobility measures (~23%, P ≤ .001). Knee extensor and flexor IF was 2-folds greater in people with COPD (P ≤ .005). Measures of knee extensor muscle strength, mass, and IF were not associated with mobility measures. CONCLUSIONS Compared with healthy controls, patients with moderate to severe COPD show marked deficits in muscle strength, mass, quality, and mobility. More studies with larger sample size are required to elucidate whether any of these muscle deficits can explain mobility impairments in COPD.

Muscle Torque Preservation and Physical Activity in Individuals with Stroke

BACKGROUND A greater percent loss of concentric versus eccentric muscle torque (i.e., relative eccentric muscle torque preservation) has been reported in the paretic limb of individuals with stroke and has been attributed to hypertonia and/or cocontractions. Stroke provides a unique condition for examining mechanisms underlying eccentric muscle preservation because both limbs experience similar amounts of general physical activity, but the paretic side is impaired directly by the brain lesion. PURPOSE The purpose of this study was to determine 1) whether eccentric preservation also exists in the nonparetic limb and 2) the relationship of eccentric or concentric torque preservation with physical activity in stroke. We hypothesized that the nonparetic muscles would demonstrate eccentric muscle preservation, which would suggest that nonneural mechanisms may also contribute to its relative preservation. METHODS Eighteen patients who had stroke and 18 healthy control subjects (age- and sex-matched) completed a physical activity questionnaire. Maximum voluntary concentric and eccentric joint torques of the ankle, knee, and hip flexors and extensors were measured using an isokinetic dynamometer at 30 degrees x s(-1) for the paretic and nonparetic muscles. Relative concentric and eccentric peak torque preservations were expressed as a percentage of control subject torque. RESULTS Relative eccentric torque was higher (more preserved) than relative concentric torque for paretic and nonparetic muscles. Physical activity correlated with paretic (r = 0.640, P = 0.001) and nonparetic concentric torque preservation (r = 0.508, P = 0.009) but not with eccentric torque preservation for either leg. CONCLUSIONS The relative preservation of eccentric torque in the nonparetic muscles suggest a role of nonneural mechanisms and could also explain the preservation observed in other chronic health conditions. Loss of concentric, but not eccentric, muscle torque was related to physical inactivity in stroke.

Preservation of eccentric torque of the knee extensors and flexors in patients with COPD.

PURPOSE The purpose of this study was to compare the concentric and eccentric torque of the knee extensors (KEs) and flexors (KFs) in persons with chronic obstructive pulmonary disease (COPD) with matched controls. Muscle volume and intramuscular fat infiltration of the thigh muscles were also compared between groups. Methods Twenty persons with moderate to severe COPD and 20 control participants, matched for age, sex, and body mass index, participated in the study. Concentric and eccentric isokinetic torque of the KEs and KFs were measured on a KinCom dynamometer. Muscle volume of the quadriceps, hamstrings, and adductors and intramuscular fat infiltration were estimated from T1-weighted magnetic resonance imaging. Muscle volume of the quadriceps and hamstrings was used to normalize torque measurements of the KEs and KFs, respectively. Results Absolute concentric and eccentric torque was lower in the COPD group than in controls. However, normalized eccentric torque was higher in persons with COPD (P < .05). Persons with COPD demonstrated lower muscle volume of all thigh muscle groups (P < .01) and greater intramuscular fat infiltration (P < .002) than controls. Conclusions Although absolute torque of the KEs and KFs are lower in persons with COPD than in controls, normalized eccentric torque is actually higher in persons with COPD. A further examination of factors that contribute to the enhancement of eccentric torque in persons with COPD is warranted.