Isometric exercise and pain in patellar tendinopathy: A randomized crossover trial.

OBJECTIVES: The aim of this study was to compare the acute effects of isometric versus dynamic resistance exercise on pain during a pain-provoking activity, and exercise-induced hypoalgesia in participants with patellar tendinopathy. DESIGN: This study was a pre-registered randomised crossover study. Participants were blinded to the study hypothesis. METHODS: Participants (N = 21) performed a single session of high load isometric resistance exercise or dynamic resistance exercise, in a randomised order separated by a 7-day washout period. Outcomes were assessed before, immediately after, and 45 min post-exercise. The primary outcome was pain intensity scored on a numeric pain rating scale (NRS; 0-10) during a pain-provoking single leg decline squat (SLDS). Secondary outcomes were pressure pain thresholds (PPTs) locally, distally and remotely, as well as tendon thickness. RESULTS: There was a significant decrease in pain NRS scores (mean reduction 0.9, NRS 95%CI 0.1-1.7; p = 0.028), and increase in PPTs at the tibialis anterior muscle (mean increase 34 kPa 95%CI 9.5-58.5; p = 0.009) immediately post-exercise. These were not sustained 45 min post-exercise for pain (NRS) or PPTs (p > 0.05). There were no differences between exercise on any outcome. CONCLUSIONS: While patients with patellar tendinopathy decreased pain during SLDS in response to resistance training, but the magnitude was small. Contraction mode may not be the most important factor in determining the magnitude of pain relieving effects. Similarly, there were only small increases in PPTs at the tibialis anterior which were not superior for isometric exercise.

Experimental Low Back Pain Decreased Trunk Muscle Activity in Currently Asymptomatic Recurrent Low Back Pain Patients During Step Tasks.

Low back pain (LBP) patients show reorganized trunk muscle activity but if similar changes are manifest in recurrent LBP (R-LBP) patients during asymptomatic periods remains unknown. In 26 healthy and 27 currently asymptomatic R-LBP participants electromyographic activity (EMG) was recorded from trunk and gluteal muscles during series of stepping up and down on a step bench before and during experimentally intramuscular induced unilateral and bilateral LBP. Pain intensity was assessed using numeric rating scale (NRS) scores. Root mean square EMG (RMS-EMG) normalized to maximal voluntary contraction EMG and pain-evoked differences from baseline (ΔRMS-EMG) were analyzed. Step task duration was calculated from foot sensors. R-LBP compared with controls showed higher baseline RMS-EMG and NRS scores of experimental pain (P < .05). In both groups, bilateral compared with unilateral experimental NRS scores were higher (P < .001) and patients compared with controls reported higher NRS scores during both pain conditions (P < .04). In patients, unilateral pain decreased ΔRMS-EMG in the Iliocostalis muscle and bilateral pain decreased ΔRMS-EMG in all back and gluteal muscles during step tasks (P < .05) compared with controls. In controls, bilateral versus unilateral experimental pain induced increased step task duration and trunk RMS-EMG whereas both pain conditions decreased step task duration and trunk RMS-EMG in R-LBP patients compared with controls (P < .05). PERSPECTIVE: Task duration and trunk muscle activity increased in controls and decreased in R-LBP patients during experimental muscle LBP. These results indicate protective strategies in controls during acute pain whereas R-LBP patients showed higher pain intensity and altered strategies that may be caused by the higher pain intensity, but the long-term consequence remains unknown.

Reorganized Trunk Muscle Activity During Multidirectional Floor Perturbations After Experimental Low Back Pain: A Comparison of Bilateral Versus Unilateral Pain.

UNLABELLED: Low back pain changes trunk muscle activity after external perturbations but the relationship between pain intensities and distributions and their effect on trunk muscle activity remains unclear. The effects of unilateral and bilateral experimental low back pain on trunk muscle activity were compared during unpredictable multidirectional surface perturbations in 19 healthy participants. Pain intensity and distribution were assessed using a visual analogue scale (VAS) and pain drawings. Root mean square (RMS) of the electromyographic (EMG) signals from 6 trunk muscles bilaterally after each perturbation was extracted and averaged across perturbations. The difference (ΔRMS-EMG) and absolute difference (absolute ΔRMS-EMG) RMS from baseline conditions were extracted for each muscle during pain conditions and averaged bilaterally for back and abdominal muscle groups. Bilateral compared with unilateral pain induced higher VAS scores (P < .005) and larger pain areas (P < .001). Significant correlation was present between VAS scores and muscle activity during unilateral (P < .001) and bilateral pain (P < .001). Compared with control injections ΔRMS-EMG increased in the back (P < .03) and abdominal (P < .05) muscles during bilateral and decreased in the back (P < .01) and abdominal (P < .01) muscles during unilateral pain. Bilateral pain caused greater absolute ΔRMS-EMG changes in the back (P < .01) and abdominal (P < .01) muscle groups than unilateral pain. PERSPECTIVE: This study provided novel observations of differential trunk muscle activity in response to perturbations dependent on pain intensity and/or pain distribution. Because of complex and variable changes the relevance of clinical examination of muscle activity during postural tasks is challenged.

Biological effects of marine diesel oil exposure in red king crab (Paralithodes camtschaticus) assessed through a water and foodborne exposure experiment.

Shipping activities are expected to increase in the Arctic Seas. Today, the majority of vessels are using marine diesel oil (MDO) as propulsion fuel. However, there is a general lack of knowledge of how cold-water marine species respond to acute exposures to MDO. Arctic red king crabs (Paralithodes camtschaticus) were exposed to mechanically dispersed MDO in a flow-through exposure system for one week followed by three weeks of recovery. Observations of increased movements in exposed crabs were interpreted as avoidance behaviour. Further, glutathione peroxidase activity increased in high exposed crab, the catalase activity showed an insignificant increase with exposure, while no differences between groups were observed for lipid peroxidation and acetylcholinesterase activity. After three weeks of recovery in clean seawater, polycyclic aromatic hydrocarbons concentrations in the crabs were significantly reduced, with no specific biomarker responses in exposed groups compared to the control. The results suggest that effects from instantaneous MDO spill only will have short-term effects on the red king crab.

Reliability of video-based quantification of the knee- and hip angle at foot strike during running.

INTRODUCTION: In clinical practice, joint kinematics during running are primarily quantified by two-dimensional (2D) video recordings and motion-analysis software. The applicability of this approach depends on the clinicians' ability to quantify kinematics in a reliable manner. The reliability of quantifying knee- and hip angles at foot strike is uninvestigated. OBJECTIVE: To investigate the intra- and inter-rater reliability within and between days of clinicians' ability to quantify the knee- and hip angles at foot strike during running. METHODS: Eighteen recreational runners were recorded twice using a clinical 2D video setup during treadmill running. Two blinded raters quantified joint angles on each video twice with freeware motion analysis software (Kinovea 0.8.15). RESULTS: The range from the lower prediction limit to the upper prediction limit of the 95% prediction interval varied three to eight degrees (within day) and nine to 14 degrees (between day) for the knee angles. Similarly, the hip angles varied three to seven degrees (within day) and nine to 11 degrees (between day). CONCLUSION: The intra- and inter rater reliability of within and between day quantifications of the knee- and hip angle based on a clinical 2D video setup is sufficient to encourage clinicians to keep using 2D motion analysis techniques in clinical practice to quantify the knee- and hip angles in healthy runners. However, the interpretation should include critical evaluation of the physical set-up of the 2D motion analysis system prior to the recordings and conclusions should take measurement variations (3-8 degrees and 9-14 degrees for within and between day, respectively) into account. LEVEL OF EVIDENCE: 3.