The effect of passive stretching on delayed onset muscle soreness, and other detrimental effects following eccentric exercise

The aim of this study was to measure if passive stretching would influence delayed onset muscle soreness (DOMS), dynamic muscle strength, plasma creatine kinase concentration (CK) and the ratio of phosphocreatine to inorganic phosphate (PCr/Pi) following eccentric exercise. Seven healthy untrained women, 28–46 years old, performed eccentric exercise with the right m. quadriceps in an isokinetic dynamometer (Biodex, angle velocity: 60°. s⁻¹) until exhaustion, in two different experiments, with an interval of 13-23 months. In both experiments the PCr/P_i ratio, dynamic muscle strength, CK and muscle pain were measured before the eccentric exercise (day 0) and the following 7 d. In the second experiment daily passive stretching (3 times of 30 s duration, with a pause of 30 s in between) of m. quadriceps was included in the protocol. The stretching was performed before and immediately after the eccentric exercise at day 0, and before measurements of the dependent variables daily for the following 7 d. The eccentric exercise alone led to significant decreases in PCr/P_i ratio ( P <0.001) and muscle strength ( P <0.001), and an increase in CK concentration ( P <0.01). All subjects reported pain in the right m. quadriceps with a peak 48 h after exercise. There was no difference in the reported variables between experiments one and two. It is concluded that passive stretching did not have any significant influence on increased plasma- CK, muscle pain, muscle strength and the PCr/P_i ratio, indicating that passive stretching after eccentric exercise cannot prevent secondary pathological alterations.     

The effects of a repeated bout of eccentric exercise on indices of muscle damage and delayed onset muscle soreness

This study examined markers of muscle damage following a repeated bout of maximal isokinetic eccentric exercise performed prior to full recovery from a previous bout. Twenty non-resistance trained volunteers were randomly assigned to a control (CON, n=10) or experimental (EXP, n=10) group. Both groups performed 36 maximal isokinetic eccentric contractions of the elbow flexors of the non-dominant arm (ECC1). The EXP group repeated the same eccentric exercise bout two days later (ECC2). Total work and peak eccentric torque were recorded during each set of ECC1 and ECC2. Isometric torque, delayed onset muscle soreness (DOMS), flexed elbow angle and plasma creatine kinase (CK) activity were measured prior to and immediately following ECC1 and ECC2. at 24h intervals for 7 days following ECC1 and finally on day 11. In both groups, all dependent variables changed significantly during the 2 days following ECC1. A further acute post-exercise impairment in isometric torque (30 +/- 5%) and flexed elbow angle (20 +/- 4%) was observed following ECC2 (p<0.05), despite EXP subjects producing uniformly lower work and peak eccentric torque values during ECC2 (p<0.05). No other significant differences between the CON and EXP groups were observed throughout the study (p>0.05). These findings suggest that when maximal isokinetic eccentric exercise is repeated two days after experiencing of contraction-induced muscle damage, the recovery time course is not significantly altered.     

Differential muscle hypertrophy and edema responses between high‐load and low‐load exercise with blood flow restriction

We sought to determine whether early increases in cross‐sectional area (CSA) of different muscles composing the quadriceps with low‐load resistance training with blood flow restriction (LL‐BFR) were mainly driven by muscle hypertrophy or by edema‐induced swelling. We also compared these changes to those promoted by high‐load resistance training (HL‐RT). In a randomized within‐subject design, fifteen healthy, untrained men were submitted to magnetic resonance imaging (MRI) for CSA and edema‐induced muscle swelling assessment (fast spin echo inversion recovery, FSE‐STIR). MRI was performed in LL‐BFR and HL‐RT at baseline (W0) and after 3 weeks (W3), with a further measure after 6 weeks (W6) for HL‐RT. Participants were also assessed at these time points for indirect muscle damage markers (range of motion, ROM; muscle soreness, SOR). CSA significantly increased for all the quadriceps muscles, for both LL‐BFR and HL‐RT at W3 (all P < .05) compared to W0. However, FSE‐STIR was elevated at W3 for all the quadriceps muscles only for HL‐RT (all P < .0001), not LL‐BFR (all P > .05). Significant increases and decreases were shown in SOR and ROM, respectively, for HL‐RT in W3 compared to W0 (both P < .05), while these changes were mitigated at W6 compared to W0 (both P > .05). No significant changes in SOR or ROM were demonstrated for LL‐BFR across the study. Early increases in CSA with LL‐BFR seem to occur without the presence of muscle edema, whereas initial gains obtained by HL‐RT were influenced by muscle edema, in addition to muscle hypertrophy.     

Calcitonin gene related peptide and neuropeptide Y in skeletal muscle after eccentric exercise: a microdialysis study

Objectives

To detect neuropeptides in human skeletal muscle at rest and after eccentric exercise.

Method

Eight healthy subjects participated in the study. Microdialysis of the distal part of the vastus lateralis of the quadriceps muscle and pain evaluation were performed immediately after eccentric exercise, after two days, and at rest. Calcitonin gene related peptide (CGRP) and neuropeptide Y (NPY), representatives of the sensory and autonomic nervous system, were analysed by radioimmunoassay.

Results

Overall, the measured concentrations were low, some even below the limit of detection. At rest, CGRP was detected in two of seven samples, but after eccentric exercise it was detected in 27 of 30 samples. At rest, all NPY concentrations were below the limit of detection, but after exercise it was found in six of 30 samples.

Conclusion

The significant increase in detectability of CGRP after eccentric exercise may be related to the increased experience of pain. Therefore the occurrence of CGRP after heavy eccentric exercise may be associated with the regulation of delayed onset muscle soreness and possibly also the stimulation of tissue regeneration.     

Frequent low-load ischemic resistance exercise to failure enhances muscle oxygen delivery and endurance capacity

This study investigated the effects of frequent low-load ischemic resistance exercise performed to failure on quadriceps size and performance, muscle activation, oxygen kinetics and cardiovascular responses. Ten healthy males performed knee-extension exercise for 4 weeks (4 sessions/week) at 15% maximal voluntary muscle contraction (MVC). One leg was trained with free blood flow (C-leg) while in the other leg (I-leg) ischemia was induced by an inflatable cuff (≥230 mmHg). Quadriceps cross-sectional area (CSA) of the I-leg increased by 3.4% (P<0.05). A tendency for smaller increase in muscle CSAs at the cuff level was observed. MVC force did not change in either leg, whereas the number of repetitions during exercise test to failure increased (P<0.01) by 63% in I-leg and 36% in C-leg. The decrease in muscle oxygenated hemoglobin concentration acquired by NIRS was attenuated (P<0.01) by 56% in I-leg and 21% in C-leg. Electromyographic amplitude of rectus femoris in I-leg was ～45% lower (P<0.025) during the ischemic test. Also, ～9% increase (P<0.05) in pre-exercise diastolic pressure was observed. In conclusion, substantial gains in muscle endurance capacity were induced, which were associated with enhanced muscle oxygen delivery. The potential negative effects of ischemic exercise with high cuff pressure on muscle and nerve and on arterial pressure regulation need further investigation.     

Computer-controlled, MR-compatible foot-pedal device to study dynamics of the muscle tendon complex under isometric, concentric, and eccentric contractions

Purpose:

To design a computer‐controlled, magnetic resonance (MR)‐compatible foot pedal device that allows in vivo mapping of changes in morphology and in strain of different musculoskeletal components of the lower leg under passive, isometric, concentric, and eccentric contractions.

Materials and Methods:

A programmable servomotor in the control room pumped hydraulic fluid to rotate a foot‐pedal inside the magnet. To validate the performance of the device, six subjects were imaged with gated velocity‐encoded phase‐contrast (VE‐PC) imaging to investigate the dynamics of muscle and aponeurotic structures.

Results:

Artifact‐free VE‐PC imaging clearly delineated different muscle compartments by differences in distribution of mechanical strains. High repeatability of contraction cycles allowed establishing that fascicles lengthened 6.1% more during passive compared with eccentric contractions. Aponeurosis separation during passive (range between three locations: ?2.6≈1.3 mm) and active (range: ?2.4≈1.6 mm) contractions were similar but significantly different from concentric (range: ?0.9≈3.3 mm), with proximal and distal regions showing mostly negative values for the first two modes, but positive for the last.

Conclusion:

The device was sufficiently robust and artifact‐free to accurately assess, using VE‐PC imaging, physiologically important structure and dynamics of the musculotendon complex. J. Magn. Reson. Imaging 2012;36:405–410. © 2012 Wiley Periodicals, Inc.

     

Renal artery stenosis: extracting quantitative parameters with a mathematical model fitted to magnetic resonance blood flow data

PURPOSE: To investigate the feasibility of quantitative parameter extraction from a mathematical model fitted to renal artery magnetic resonance flow data. MATERIAL AND METHODS: A total of 16 subjects, eight patients, and eight normal controls, were examined with cine phase-contrast velocity measurements, and blood flow data from the aorta and both renal arteries were extracted by means of contour detection. A mathematical model with eight parameters describing the time, duration, and amplitude of the systolic acceleration and the diastolic deceleration was fitted to the aorta and renal artery blood flow data from each subject. The curve fitting was evaluated with R(2) values. Statistical analysis was performed with unpaired Wilcoxon tests and stepwise logistic regression. RESULTS: A total of three data sets out of 48 yielded R(2) values below 0.80 and were considered unreliable for parameter estimation. Basal flow was significantly, and systolic peak amplitude almost significantly, lower in stenotic arteries. Logistic regression indicated that two parameters describing basal flow and the duration of acceleration can accurately predict stenosis. CONCLUSION: The results suggest that it is technically feasible to fit a mathematical model to renal blood flow data, extracting quantitative parameters that may prove useful for quantification and diagnosis of renal artery stenosis.     

Transit delay and flow quantification in muscle with continuous arterial spin labeling perfusion-MRI

PURPOSE: To test the hypothesis that flow measurements using continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI) in muscle depend upon transit delay, and examine the repeatability of CASL measurements. MATERIALS AND METHODS: A total of 23 healthy subjects underwent CASL imaging of the calf, foot, and forearm with varying postlabeling delay (PLD = 1000, 1500, and 1900 msec). Experiments were conducted on a 3.0T system. An orthopedic tourniquet system was employed to create a five-minute period of ischemia followed by a transient hyperemic flow. Imaging commenced two minutes prior to cuff inflation and ended three minutes after cuff release. RESULTS: CASL was found able to well resolve the time course of the hyperemic flow pattern with an effective TR of 16 seconds, although we were unable to establish that a plateau had been reached in the flow measurements even at a PLD as long as 1900 msec. Peak hyperemic flow measurements compared favorably with those obtained with contrast-enhanced (CE) MRI following a similar period of ischemia. Region-of-interest (ROI)-based repeated measurements varied by approximately 20% over a period of one hour. CONCLUSION: In all anatomic regions studied, flow measurements were found to increase with PLD, suggesting the prolonged transit delay in muscle.     

Regional heterogeneity of resting perfusion in hypertrophic cardiomyopathy is related to delayed contrast enhancement but not to systolic function: A PET and MRI study

Background  Regional differences in resting myocardial blood flow (MBF) have been observed in patients with hypertrophic cardiomyopathy (HCM), but their determinants are currently unknown. This study verifies whether MBF at rest in HCM is related to delayed contrast enhancement (DCE) or regional systolic function (or both) as determined by magnetic resonance imaging. Methods and Results  Fourteen patients with HCM were studied. MBF was measured with positron emission tomography by use of oxygen 15-labeled water. DCE and tissue tagging, to calculate end-systolic circumferential shortening (Ecc), were obtained with magnetic resonance imaging. The mean resting MBF was 0.78 ± 0.19 mL . min^-1 . mL^-1, and there was a trend toward reduced MBF in the septum (0.72 ± 0.11 mL . min^-1 . mL^-1) compared with that in the lateral wall (0.84 ± 0.29 mL . min^-1 . mL^-1) (P -.092). The distribution patterns of DCE and Ecc were both heterogeneous, displaying significantly increased enhancement and impaired regional systolic function in the hypertrophic septum compared with the lateral wall (both P < .001). Resting MBF was inversely related to the extent of DCE (r - 0.30, P < .001), whereas MBF was not significantly related to Ecc (r -0.15, P - .072). Conclusions  Regional heterogeneity of resting perfusion in HCM is related to the extent of DCE but not to regional systolic function. Willem G. van Dockum is supported by the Netherlands Heart Foundation (grant 1999B203).     

Functional assessment of the kidney from magnetic resonance and computed tomography renography: impulse retention approach to a multicompartment model

A three-compartment model is proposed for analyzing magnetic resonance renography (MRR) and computed tomography renography (CTR) data to derive clinically useful parameters such as glomerular filtration rate (GFR) and renal plasma flow (RPF). The model fits the convolution of the measured input and the predefined impulse retention functions to the measured tissue curves. A MRR study of 10 patients showed that relative root mean square errors by the model were significantly lower than errors for a previously reported three-compartmental model (11.6% +/- 4.9 vs 15.5% +/- 4.1; P < 0.001). GFR estimates correlated well with reference values by (99m)Tc-DTPA scintigraphy (correlation coefficient r = 0.82), and for RPF, r = 0.80. Parameter-sensitivity analysis and Monte Carlo simulation indicated that model parameters could be reliably identified. When the model was applied to CTR in five pigs, expected increases in RPF and GFR due to acetylcholine were detected with greater consistency than with the previous model. These results support the reliability and validity of the new model in computing GFR, RPF, and renal mean transit times from MR and CT data.     

Blood oxygenation level-dependent (BOLD) MRI of human skeletal muscle at 1.5 and 3 T

Purpose:

To evaluate the dependence of skeletal muscle blood oxygenation level‐dependent (BOLD) effect and time course characteristics on magnetic field strength in healthy volunteers using an ischemia/reactive hyperemia paradigm.

Materials and Methods:

Two consecutive skeletal muscle BOLD magnetic resonance imaging (MRI) measurements in eight healthy volunteers were performed on 1.5 T and 3.0 T whole‐body MRI scanners. For both measurements a fat‐saturated multi‐shot multiecho gradient‐echo EPI sequence was applied. Temporary vascular occlusion was induced by suprasystolic cuff compression of the thigh. T2* time courses were obtained from two different calf muscles and characterized by typical curve parameters. Ischemia‐ and hyperemia‐induced changes in R2* (ΔR2*) were calculated for both muscles in each volunteer at the two field strengths.

Results:

Skeletal muscle BOLD changes are dependent on magnetic field strength as the ratio ΔR2*(3.0 T)/ΔR2*(1.5 T) was found to range between 1.6 and 2.2. Regarding time course characteristics, significantly higher relative T2* changes were found in both muscles at 3.0 T.

Conclusion:

The present study shows an approximately linear field strength dependence of ΔR2* in the skeletal muscle in response to ischemia and reactive hyperemia. Using higher magnetic fields is advisable for future BOLD imaging studies of peripheral limb pathologies. J. Magn. Reson. Imaging 2012;35:1227‐1232. © 2012 Wiley Periodicals, Inc.     

Detection of lactate with a hadamard slice selected,selective multiple quantum coherence,chemical shift imaging sequence (HDMD‐SelMQC‐CSI) on a clinical MRI scanner: Application to tumors and muscle ischemia

Lactate is an important metabolite in normal and malignant tissues detectable by NMR spectroscopy; however, it has been difficult to clinically detect the lactate methyl resonance because it is obscured by lipid resonances. The selective homonuclear multiple quantum coherence transfer technique offers a method for distinguishing lipid and lactate resonances. We implemented a three‐dimensional selective homonuclear multiple quantum coherence transfer version with Hadamard slice selection and two‐dimensional phase encoding (Hadamard encoded–selective homonuclear multiple quantum coherence transfer–chemical shift imaging) on a conventional clinical MR scanner. Hadamard slice selection is explained and demonstrated in vivo. This is followed by 1‐cm³ resolution lactate imaging with detection to 5‐mM concentration in 20 min on a 3‐T clinical scanner. An analysis of QSel gradient duration and amplitude effects on lactate and lipid signal is presented. To demonstrate clinical feasibility, a 5‐min lactate scan of a patient with a non‐Hodgkin's lymphoma in the superficial thigh is reported. The elevated lactate signal coincides with the T₂‐weighted image of this tumor. As a test of selective homonuclear multiple quantum coherence transfer sensitivity, a thigh tourniquet was applied to a normal volunteer and an increase in lactate was detected immediately after tourniquet flow constriction. In conclusion, the Hadamard encoded–selective homonuclear multiple quantum coherence transfer–chemical shift imaging sequence is demonstrated on a phantom and in two lipid‐rich, clinically relevant, in vivo conditions. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.