Anna Jaskólska

Adaptation to a standardized training program and changes in fitness in a large, heterogeneous population : the HERITAGE Family Study

PURPOSE This paper describes the variations in response to a standardized, computer-controlled training program. METHODS Steady-state heart rate (HR) and oxygen intake (VO2) of 614 healthy, sedentary men and women aged 16-65 yr were measured during three cycle ergometer exercise tests. The HR associated with 55, 65, 70, and 75% of each subjects pretraining VO2max was used to prescribe exercise intensity. Subjects exercised three times a week, beginning at a HR associated with 55% VO2max for 30 min. Duration and intensity was gradually increased over 20 wk of training. The duration and HR of each training session were controlled by a computer. RESULTS Using the linear relationship between HR, VO2 and power output (PO), PO were predicted for each of 60 training sessions at the respective programmed HR. The average ratio of the actual training HR to programmed HR was 0.99. It was hypothesized that participants whose actual training PO exceeded their predicted PO would improve VO2max more than those whose actual PO was less than their predicted PO. Using the ratio of actual/predicted PO determined after the training was over, participants were arbitrarily assigned to three groups: 128 participants had low (LO) ratios (0.65-0.84), 408 had average (AV) ratios (0.85-1.14), and 78 had high (HI) ratios (1.15-1.34). Secondary analysis showed that the training program significantly increased mean VO2max of all three groups. Those who had a smaller increase in training PO (LO) had significantly less increase in VO2max than those with larger increases in PO (HI). CONCLUSION People who exercise at a HR associated with the same %VO2max can vary substantially in their training PO, in their rate of increase in PO over a 20-wk training program, and in improvement of their VO2max.

Reproducibility of maximal exercise test data in the Heritage Family Study

PURPOSE The reproducibility of responses to maximal cycle ergometer testing was determined using data from the HERITAGE Family study at four Clinical Centers in the United States and Canada. METHODS Reproducibility was determined from maximal exercise test data obtained a) on 2 d in a sample of 390 subjects (198 men and 192 women), b) across 4 d in an Intracenter Quality Control (ICQC) substudy with 55 subjects who were not part of the main study, and c) across 2 wk in a Traveling Crew Quality Control (TCQC) substudy with the same eight subjects who were tested at each of the four centers. Reproducibility was evaluated using technical errors, coefficients of variation (CV) for repeated measures, and intraclass correlation coefficients (ICC) for selected variables obtained on the main cohort, as well as on the ICQC and TCQC substudies. RESULTS With the exception of systolic and diastolic blood pressures and respiratory exchange ratio, all the other variables (heart rate, ventilation, VO2, and VCO2) were highly reproducible, with CV below 10% and ICC over 0.86. These results were similar to those previously reported on the same subjects at a submaximal power output associated with 60% VO2max. Results were consistent for the main cohort, the ICQC sample, the TCQC sample, and across all four Clinical Centers. CONCLUSIONS Day-to-day variations are small and reproducibility is high for maximal values of heart rate, ventilation, VO2 and VCO2 at each of the four Clinical Centers of the HERITAGE Family Study.

Mechanomyography and electromyography during and after fatiguing shoulder eccentric contractions in males and females.

The aim of this study was to investigate changes in mechanomyographic (MMG) and the surface electromyographic (EMG) signals during and after fatiguing shoulder eccentric contractions in a group consisting of 12 males and 12 females. Exerted force, MMG, EMG, pain and rate of perceived exertion were assessed before, during and after repeated high‐intensity eccentric exercises. Bouts of eccentric contractions caused a decrease in the exerted force for males (P<0.05) and an increase in the rate of perceived exertion and pain for both genders (P<0.05). During eccentric exercise, the root mean square (RMS) values of the MMG signal increased (P<0.05). The mean power frequency (MPF) values of the EMG signal decreased at the end of each eccentric bout for both genders (P<0.05); the decrease was higher for females compared with males (P<0.05). Immediately after eccentric exercise in static abduction of the upper limbs, the MMG RMS and MPF values increased (P<0.05). The present study showed that (1) neuromuscular changes associated with pain and changes in muscle stiffness and (2) changes in motor units strategy during fatigue development in shoulder muscle are reflected in the MMG and EMG signals.

Weakening of Synergist Muscle Coupling During Reaching Movement in Stroke Patients

Background. After hemiparetic stroke, coordination of the shoulder flexor and elbow extensor muscles during a reaching movement is impaired and contributes to poor performance. Objective. The aim was to determine whether functional coupling between electromyographic signals of synergist muscles during reaching was weakened in stroke patients who had poor motor coordination. Methods. Surface electromyography (EMG) from the anterior deltoid, triceps brachii, biceps brachii, pectoralis major, supraspinatus, and latissimus dorsi of the affected upper limb in 11 stroke patients (mean Fugl-Meyer upper extremity score 27 ± 8) and in the dominant arm of 8 healthy controls were measured. Results. Coherence between the EMG of the anterior deltoid and triceps brachii, 2 synergists for reaching, was lower in patients compared with controls, in the 0- to 11-Hz range. Detailed segmented frequency-range analysis indicated significant differences in the coherence between groups in 0- to 3.9-Hz and 4- to 7.9-Hz ranges. Conclusions. This weakened functional coupling may contribute to poor reaching performance and could be a consequence of a loss of common drive at the frequency bands as a result of interruption of information flow in the corticospinal pathway.

Higher Muscle Passive Stiffness in Parkinson's Disease Patients Than in Controls Measured by Myotonometry

OBJECTIVE To assess muscle passive stiffness in medicated Parkinsons disease patients using myotonometry. DESIGN Case-control study. SETTING Kinesiology laboratory. PARTICIPANTS Women with Parkinsons disease (PD) (n=8) and healthy matched elderly women (controls) (n=10) (mean age: PD, 77+/-3y; controls, 77+/-4y). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Passive stiffness of relaxed biceps brachii (BB) muscle was measured using myotonometry. Additionally, surface electromyographic and mechanomyographic signals were recorded from the muscle at rest, and amplitude of those signals was analyzed offline. RESULTS The values of BB muscle passive stiffness were significantly (P=.004) higher in PD than in the controls, with a statistically significant influence of parkinsonian rigidity score (Unified Parkinsons Disease Rating Scale) on intergroup differences (P<.001). The Spearman correlation coefficient rho value showed a significant (P=.005) positive relationship (rho=.866) between the parkinsonian rigidity score and passive stiffness values of BB in PD. The groups did not differ significantly in the electromyogram amplitude (P=.631) and mechanomyogram amplitude (P=.593) of the BB muscle, and values of these parameters did not correlate significantly with rigidity score (P=.555, P=.745, respectively) in the patients. CONCLUSIONS Myotonometer is a sensitive enough tool to show that PD patients have higher muscle passive stiffness than healthy controls.

Myometry revealed medication-induced decrease in resting skeletal muscle stiffness in Parkinson's disease patients

BACKGROUND Based on combined analysis of clinical assessment of parkinsonian rigidity (constant resistance force generated during passive movement in a joint), electromyography and/or dynamometry many studies showed objectively that anti-parkinsonian medication decreases the rigidity in Parkinsons disease (PD). Rigidity-related changes in resting muscle stiffness (changed muscles mechanical property related to its structural changes and changed neural drive) in PD patients have been revealed by myometry, a simple, sensitive, and reliable method for measuring mechanical properties in human soft tissues. However, an application of myometry in estimation of medication effects on the PD rigidity-related muscle stiffness has not been reported yet. Therefore, our study aimed to assess medication-induced changes in resting muscle stiffness in PD patients using myometry. METHODS We measured resting muscle stiffness by myometry and recorded a surface electromyogram of relaxed biceps brachii, brachioradialis and triceps brachii muscles in ten patients with PD (age: 51-80 years; Hoehn and Yahr stage: 2.5-4) during medication on-phase (when subjects felt best comfort and fitness after medication: Levodopa, Piribedil, Ropinirol) and medication off-phase (12h after withdrawal of the medication). FINDINGS Our patients had significantly lower myometric stiffness and electromyogram amplitude in all tested muscles, and also lower clinical rigidity scores during the medication on-phase compared with the medication off-phase. INTERPRETATION Myometry revealed that anti-parkinsonian medication decreases not only rigidity in PD, but also rigidity-related stiffness in resting skeletal muscles in PD patients. These findings show that myometry can enrich neurological practice, by allowing objective and reliable assessment of parkinsonian rigidity treatment effectiveness.

EMG and MMG of synergists and antagonists during relaxation at three joint angles

The aim of the study was to estimate the influence of force changes during relaxation from maximal voluntary contraction (MVC) of elbow flexors on electrical (EMG) and mechanical (MMG) activity of synergists and anatgonists at different joint angles. Repeated studies were conducted on 22 young female students to estimate the EMG and MMG activity of the biceps brachii (BB), brachioradialis (BR), and triceps brachii (TB) muscles during relaxation from MVC at an optimal angle (the angle at which a subject achieved MVC=Lo), as well as at angles that were smaller (Ls=Lo−30°) and bigger (Ll=Lo+30°). Four testing sessions consisted of 2-s or 3-s MVC at each angle with simultaneous recording of EMG and MMG signals from BB, BR, and TB muscles. The EMG/MMG probes were used to record EMG and MMG signals. The results showed that the slow relaxation rate was related to a percentage decrease of the EMG amplitude (as measured by root mean square; EMG RMS) of the synergists, while the fast relaxation was related to the EMG RMS of the antagonist, independent of the joint angle. The MMG amplitude (MMG RMS) increased gradually during slow and fast relaxation (compared to the MMG RMS at MVC), indicating a bigger muscle oscillation during relaxation; the changes were related to the muscle tested and joint angle. It was found that, during the slow relaxation, the MMG RMS reflects the force amplitude changes in the BB muscle and the velocity of force changes in the BB and TB muscle (but not in the BR). During the fast relaxation, the MMG amplitude reflects a change in muscle force in the TB and BB muscles (but not in the BR), and the velocity of force changes in the synergists (not in the antagonist). The different contribution of the force and velocity of force changes during slow and fast relaxation to the MMG signal in the three muscle tested can be related to the different deactivation time of each muscle. In conclusion, the present results indicate that MMG recordings might be useful to measure the fast relaxation of individual muscle during voluntary contraction, but this needs be tested on isolated muscle.

Increased muscle belly and tendon stiffness in patients with Parkinson's disease, as measured by myotonometry

Based on Daviss law, greater tonus of the muscle belly in individuals with Parkinsons disease can create greater tension in the tendon, leading to structural adjustment and an increase in tendon stiffness. Our study aimed to separately assess passive stiffness in the muscle belly and tendon in medicated patients with Parkinsons disease, using myotonometry.

Muscle passive stiffness increases less after the second bout of eccentric exercise compared to the first bout

OBJECTIVES The purpose of this study was to assess if the protective adaptation after eccentric exercise affects changes in passive stiffness of the biceps brachii muscle. DESIGN A within-group repeated measures design was used to compare changes in passive muscle stiffness after eccentric exercise between the first and second bouts separated by 2-3 weeks. METHOD Maximal isometric torque, passive muscle stiffness and soreness were measured on the right elbow flexors in 14 untrained male volunteers before, immediately after, 24, 48 and 120 h following each bout of eccentric exercise that consisted of 30 repetitions of lowering a dumbbell adjusted to 75% of each individuals maximal isometric torque. RESULTS Maximal isometric torque reduced immediately after the first bout by 24 ± 11% (mean ± SD; P < 0.05) and remained decreased for the next 120 h (~23%). Passive muscle stiffness immediately increased from 223 ± 19 N/m to 254 ± 22 N/m (P < 0.05) and remained higher for 120 h. After the second bout maximal isometric torque decreased 21 ± 13%, and 48 h later recovered to pre-exercise level (P < 0.05). Increase in passive muscle stiffness was attenuated after the second bout (238 ± 17 N/m; P < 0.05). The perceived muscle soreness was lower after the second bout. CONCLUSIONS Smaller increases in passive muscle stiffness and soreness, and faster maximal isometric torque recovery after the second bout of eccentric exercise could result from adaptation process that occurred after the first bout.

Tensegrity principle in massage demonstrated by electro- and mechanomyography

Based on a tensegrity principle, direct or indirect connections between fascia or muscles which stretch the aponeurosis or intermuscular septum may allow the transfer of tension over long distances, without loss of muscle force produced during rest and activity. The present study aimed to test an effect of massage on electrical (EMG) and mechanical (MMG) activities of a muscle lying distant, but indirectly connected to, the massaged muscle. Thirty-three healthy men participated in the study. To record the activity of the middle deltoid muscle the brachioradialis was massaged, and for the tensor fasciae latae-the peroneal muscles were massaged. An EMG/MMG hybrid probe was used to detect EMG and MMG signals from the middle deltoid and tensor fasciae latae muscles. The EMG amplitude increased during massage in the tensor fasciae lata only, while the MMG amplitude increased significantly in both muscles. It was concluded that there was an electrical as well as a mechanical response of muscle connected indirectly by structural elements with the muscle being massaged indicating an application for the tensegrity principle in massage therapy. It also has a practical importance, because it provides a means for a physiotherapist to influence adverse muscle tension by massaging another distant muscle.