Interventions to enhance recovery in healthy workers; a scoping review.

BACKGROUND: Faster recovery from work may help to prevent work-related ill health. AIMS: To provide a preliminary assessment of the range and nature of interventions that aim to improve recovery from cognitive and physical work. METHODS: A scoping review to examine the range and nature of the evidence, to identify gaps in the evidence base and to provide input for systematic reviews. We searched for workplace intervention studies that aimed at enhancing recovery. We used an iterative method common in qualitative research to obtain an overview of study elements, including intervention content, design, theory, measurements, effects and cost-effectiveness. RESULTS: We found 28 studies evaluating seven types of interventions mostly using a randomized controlled study design. For person-directed interventions, we found relaxation techniques, training of recovery experiences, promotion of physical activity and stress management. For work-directed interventions, there were participatory changes, work-break schedules and task variation. Most interventions were based on the conservation of resources and affect-regulation theories, none were based on the effort-recovery theory. The need for recovery (NfR) and the recovery experiences questionnaires (REQ) were used most often. Study authors reported a beneficial effect of the intervention in 14 of 26 published studies. None of the studies that used the NfR scale found a beneficial effect, whereas studies that used the REQ showed beneficial effects. Three studies indicated that interventions were not cost-effective. CONCLUSIONS: Feasible and possibly effective interventions are available for improving recovery from cognitive and physical workload. Systematic reviews are needed to determine their effectiveness.

Effects of training on functional variables of muscles in reared Atlantic salmon Salmo salar smolts: connection to downstream migration pattern.

The relative amount of muscle contraction regulating dihydropyridine and ryanodine receptors in the swimming muscles of trained reared Atlantic salmon Salmo salar smolts was compared with those of untrained and wild smolts. After an optimized 2 week training period, i.e. swimming with a velocity of 1·5 body lengths per second for 6 h per day, the level of both receptors was significantly higher in the muscles of trained S. salar than in the untrained ones before they were released into the natural environment. This difference persisted after downstream migration in the river. The highest level of receptors was observed in wild S. salar. Swimming performance was also higher in trained fish compared to untrained ones. Furthermore, swimming performance was positively associated with the level of receptors in both red and white muscle types. Downstream migration after release into the wild was significantly slower in trained smolts than in untrained fish. This indicates that trained smolts were most probably swimming harder against the current in the river than untrained smolts. The possible advantages for a slower migration in the river are discussed. This study shows that the prerequisites for effective contraction of the swimming muscles are better met in trained S. salar compared to untrained fish, and the muscles of trained smolts more closely resemble those of wild smolts. The results also imply that the capacity of untrained, reared smolts to swim against the current is not equal to that of their trained or wild counterparts which affects the downstream migration pattern of S. salar smolts.

Ultrastructural differences and histochemical characteristics in swimming muscles between wild and reared Atlantic salmon.

AIM: The swimming capacity of wild and reared fish differs. Whether the differences are associated with metabolic, contractile or structural variation in swimming musculature is unknown. In the present study, some aspects of contractile machinery in swimming muscles of wild and reared salmon are compared. METHODS: Several morphological parameters and key enzyme activities were measured using electron microscopy and histochemical methods. RESULTS: The density and size of the mitochondria was significantly higher in the muscle samples from wild fish when compared with the reared ones. Similar variability was also seen in the density of triads. Conversely, the size and density of lipid droplets was significantly lower in the red muscle of wild vs. reared salmon. The densities of two excitation contraction coupling components, dihydropyridine and ryanodine receptor, were considerably higher in swimming muscles of wild salmon than in reared fish. A similar difference was observed in the activities of aerobic enzymes. Moreover, oxygen consumption followed the same pattern, being significantly higher in the samples of wild salmon. Phosphorylase activity was, on the other hand, significantly lower in the muscles of wild fish. CONCLUSIONS: There are significant differences in morphology, Ca(2+)-regulating capacity and enzyme activities in swimming muscles between wild and reared salmon. These results provide evidence that the prerequisites for efficient contraction of the swimming muscles are better met in wild than in reared salmon. Importantly, the results also suggest that the observed variation is a major contributing factor to the difference in the swimming capacity between wild and hatchery-reared salmon.

Testosterone and Ca2+ regulation in skeletal muscle.

The aim of this study was to examine the effect of testosterone treatment on the expression of dihydropyridine and ryanodine receptors in skeletal muscle of mouse. Furthermore, the effects of training, a method also known to elevate the plasma testosterone level, were studied and compared to the effects of pure testosterone administration. Male mice were either administered with testosterone or trained with treadmill. After 6 weeks, hindlimb muscles were excised and the expression of receptors was measured by Western blotting. Furthermore, the alterations in myosin heavy chain phenotypes were studied. In general, both training and testosterone administration induced changes in the expression of both receptors and in myosin heavy chain composition. In testosterone treated mice the expression of dihydropyridine receptor in extensor digitorum longus was higher compared to the control ones (38.9 %, p = 0.026). In soleus the expression was quite the contrary (- 27.3 %, p = 0.044), as was the case with ryanodine receptor (- 51.4 %, p = 0.012). The amount of ryanodine receptors was higher in rectus femoris (144.0 %, p = 0.044) and plantaris (48.1 %, p = 0.037) in testosterone treated mice. In trained mice, the expression of ryanodine receptor was significantly higher in gastrocnemius (27.6 %, p = 0.018), soleus (57.2 %, p = 0.025), plantaris (28.5 %, p = 0.009) and extensor digitorum longus (94.8 %, p = 0.009) than in the control ones. No differences were observed in the dihydropyridine receptor level. To conclude, training has a more important role in skeletal muscle adaptation compared to increased plasma testosterone level. However, in postural muscles both treatments have comparable effects.

Vildagliptin therapy reduces postprandial intestinal triglyceride-rich lipoprotein particles in patients with type 2 diabetes.

AIMS/HYPOTHESIS: We assessed the effects of vildagliptin, a novel dipeptidyl peptidase IV inhibitor, on postprandial lipid and lipoprotein metabolism in patients with type 2 diabetes. SUBJECTS, MATERIALS AND METHODS: This was a single-centre, randomised, double-blind study in drug-naive patients with type 2 diabetes. Patients received vildagliptin (50 mg twice daily, n=15) or placebo (n=16) for 4 weeks. Triglyceride, cholesterol, lipoprotein, glucose, insulin, glucagon and glucagon-like peptide-1 (GLP-1) responses to a fat-rich mixed meal were determined for 8 h postprandially before and after 4 weeks of treatment. RESULTS: Relative to placebo, 4 weeks of treatment with vildagliptin decreased the AUC(0-8h) for total trigyceride by 22+/-11% (p=0.037), the incremental AUC(0-8h) (IAUC(0-8h)) for total triglyceride by 85+/-47% (p=0.065), the AUC(0-8h) for chylomicron triglyceride by 65+/-19% (p=0.001) and the IAUC(0-8h) for chylomicron triglyceride by 91+/-28% (p=0.002). This was associated with a decrease in chylomicron apolipoprotein B-48 (AUC(0-8h), -1.0+/-0.5 mg l(-1) h, p=0.037) and chylomicron cholesterol (AUC(0-8h), -0.14+/-0.07 mmol l(-1) h, p=0.046). Consistent with previous studies, 4 weeks of treatment with vildagliptin also increased intact GLP-1, suppressed inappropriate glucagon secretion, decreased fasting and postprandial glucose, and decreased HbA(1c) from a baseline of 6.7% (change, -0.4+/-0.1%, p<0.001), all relative to placebo. CONCLUSIONS/INTERPRETATION: Treatment with vildagliptin for 4 weeks improves postprandial plasma triglyceride and apolipoprotein B-48-containing triglyceride-rich lipoprotein particle metabolism after a fat-rich meal. The mechanisms underlying the effects of this dipeptidyl peptidase IV inhibitor on postprandial lipid metabolism remain to be explored.

Expression of L-type calcium channels associated with postnatal development of skeletal muscle function in mouse.

Several factors have an influence on the improvement of muscle activity and motor co-ordination of mammals during post-natal development. One of them is voltage sensitive L-type calcium channel function. In striated muscles of adult mammals these channels are located in T-tubule membranes thus linking the on-coming action potential to the molecular process of muscle contraction. The postnatal development of L-type calcium channels is therefore critical not only for contraction but also for all subsequent motor learning. We used high affinity enantiomer of dihydropyridine labelled with a fluorophore in order to show the relative amount of L-type calcium channels by histofluorescence in tissue. We found by qualitative microscopical analysis that the amount of L-type calcium channels increased during the postnatal development in the mouse skeletal muscle (m. rectus femoris and m. gastrocnemius). We also noted variation between different fibre types in the increase of the amount of L-type calcium channels, as judged by the intensity of histofluorescence. We showed by histochemical staining and statistical analysis that the high density of L-type calcium channels in adult muscles is correlated with fast oxidative glycolytic fibre type of striated muscles rather than slow oxidative or fast glycolytic fibres. Based on this finding we propose that the development of L-type calcium channels can be considered as one of the factors determining the different physiological properties of fibre types.