Low-intensity Exercise Protocol Research Articles

Impact of Low Intensity Exercise on Liver Enzymes (ALT & ALP)

This particular research study was basically carried out for the purpose to examine the impact of low intensity exercise on two particular liver enzymes i.e. alanine transaminase (ALT) and alkaline phosphate (ALP). 20 Non sportsmen were selected as subjects of the study (n=20, age 20 to 30 years (20.95±3.79), Body Mass Index (BMI) from 18 to 30 (25.90±5.54). Similarly the subjects were divided into two groups (Experimental Group and Control Group) through the application of International Physical Activity Questionnaire (IPAQ) and measurement of Maximum Heart Rate (MHR). 12 weeks self-made low intensity exercise protocol was applied to an experimental group. 5ml blood was collected from all subjects to measure the effect of low intensity exercise on ALT and ALP. The data of pre and post-test were processed through SPSS version 24. Based on analysis and findings, the researcher concluded that in experimental group (EXG) the level of ALT and ALP was found significantly higher (p<0.05) as compared to control group (CG). Based on conclusion, it is hereby recommended by the researcher that for the purpose to promote the functional capacity of liver, low as well as moderate intensity exercise should be performed on daily basis. In addition, in this study due to lack of financial resources, two basic liver enzymes i.e.ALT and ALP were measured, therefore the other enzymes like as AST and bilirubin also need to be examined in such other research studies.

Energy matching of a high-intensity exercise protocol with a low-intensity exercise protocol in young people

© 2021 Springer Nature Switzerland AG. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1007/s11332-021-00774-3

The influence of maximal and submaximal cyclic concentric and eccentric exercise on chondrocyte death and synovial fluid proteins in the rabbit knee

BackgroundMechanical stimulation of joints regulates the biosynthetic activity of chondrocytes. It has been argued that excessive loading might cause chondrocyte death, leading to degeneration of cartilage and cause osteoarthritis. The aims of this study were to apply a high, short-term loading, and a low intensity, long-term loading protocol to intact joints in life animals and determine changes in synovial fluid and the percentage of dead cells in rabbit knee cartilage. MethodNine rabbits were subjected to unilateral exercise loading consisting of five sets of 10 maximal eccentric knee contractions. Another 6 rabbits were subjected to submaximal concentric contractions for 30 min at 20% of the maximum isometric knee extensor force. Contralateral joints served as unloaded controls. Cell viability was assessed using confocal microscopy. Synovial fluid was analyzed for total protein concentration and total number of identifiable proteins and was compared to protein content of control rabbits (n = 4). FindingsNeither the high-intensity, short-term nor the low-intensity, long-term loading protocol caused increased chondrocyte death compared to the unloaded control joints. Total synovial fluid protein concentration was the same before and after exercise. Following the high-intensity exercise protocol, the number of identifiable proteins was decreased, while following the low-intensity exercise protocol, the number of identifiable proteins was increased compared to control. InterpretationChondrocytes are well protected in the intact joint and withstood maximal eccentric muscular loading, and maximal endurance loading. Synovial fluid protein content was changed after exercise, and these changes depended crucially on the type of loading.

Plasma citrulline concentration, a marker for intestinal functionality, reflects exercise intensity in healthy young men

Plasma citrulline concentration is considered to be a marker for enterocyte metabolic mass and to reflect its reduction as may occur during intestinal dysfunction. Strenuous exercise can act as a stressor to induce small intestinal injury. Our previous studies suggest that this comprises the intestinal ability to produce citrulline from a glutamine-rich protein bolus. In this study we investigated the effects of different exercise intensities and hydration state on citrulline and iFABP levels following a post-exercise glutamine bolus in healthy young men. Fifteen healthy young men (20-35yrs, VO2 max 56.9±3.9mlkg-1min-1) performed in a randomly assigned cross-over design, a rest (protocol 1) and four cycle ergometer protocols. The volunteers cycled submaximal at different percentages of their individual pre-assessed maximum workload (Wmax): 70% Wmax in hydrated (protocol 2) and dehydrated state (protocol 3), 50% Wmax (protocol 4) and intermittent 85/55% Wmax in blocks of 2min (protocol 5). Immediately after 1h exercise or rest, subjects were given a glutamine bolus with added alanine as an iso-caloric internal standard (7.5g of each amino acid). Blood samples were collected before, during and after rest or exercise, up to 24h post onset of the experiment. Amino acids and urea were analysed as metabolic markers, creatine phosphokinase and iFABP as markers of muscle and intestinal damage, respectively. Data were analysed using a multilevel mixed linear statistical model. p values were corrected for multiple testing. Citrulline levels already increased before glutamine supplementation during normal hydrated exercise, while this was not observed in the dehydrated and rest protocols. The low intensity exercise protocol (50% Wmax) showed the highest increase in citrulline levels both during exercise (43.83μmol/L±2.63 (p<0.001)) and after glutamine consumption (50.54μmol/L±2.62) compared to the rest protocol (28.97μmol/L±1.503 and 41.65μmol/L±1.96, respectively, p<0.05). However, following strenuous exercise at 70% Wmax in the dehydrated state, citrulline levels did not increase during exercise and less after the glutamine consumption when compared to the resting condition and hydrated protocols. In line with this, serum iFABP levels were the highest with the strenuous dehydrated protocol (1443.72μmol/L±249.9, p<0.001), followed by the high intensity exercise at 70% Wmax in the hydrated condition. Exercise induces an increase in plasma citrulline, irrespective of a glutamine bolus. Theextent to which this occurs is dependent on exercise intensity and the hydration state of the subjects. The same holds true for both the post-exercise increase in citrulline levels following glutamine supplementation and serum iFABP levels. These data indicate that citrulline release during exercise and after an oral glutamine bolus might be dependent on the intestinal health state and therefore on intestinal functionality. Glutamine is known to play a major role in intestinal physiology and the maintenance of gut health and barrier function. Together, this suggests that in clinical practice, a glutamine bolus to increase citrulline levels after exercise might be preferable compared to supplementing citrulline itself. To our knowledge this is the first time that exercise workload-related effects on plasma citrulline are reported in relation to intestinal damage.

One-day low-intensity combined arm-leg (Cruiser) ergometer exercise intervention: cardiorespiratory strain and gross mechanical efficiency in one-legged and two-legged exercise.

This study aims to research whether there is a difference in cardiorespiratory variables and gross mechanical efficiency (GE) in healthy individuals during low-intensity one-legged and two-legged exercise on the combined arm-leg (Cruiser) ergometer and whether motor learning occurs. The outcome of this study will support the use of the Cruiser ergometer in future as a testing and training instrument in the rehabilitation of patients with a lower limb amputation. Twenty-eight healthy men participated in this randomized-controlled trial. One group (n=14) used one leg and both arms during the exercise and the other group (n=14) used both legs and both arms. All participants performed a 1-day low-intensity exercise protocol. This included a standardized pretest and post-test of three bouts of 4 min exercise at 40 W and an exercise intervention of seven bouts of 2×4 min exercise at 40 W. The one-legged and two-legged group differed significantly in the heart rate and GE between the pretest and post-test. At the post-test, the one-legged group showed motor learning. GE improved significantly in both groups over the duration of the three exercise bouts of the pretest, but it did not improve during the post-test. There are differences in cardiorespiratory variables and GE between one-legged and two-legged exercise on the Cruiser ergometer. When using this ergometer in the rehabilitation of patients with a lower limb amputation, it is important to consider these differences and the occurrence of motor learning.

Predictive value of strength loss as an indicator of muscle damage across multiple drop jumps

The aim of the present study was to compare the time-course of indirect symptoms of exercise-induced muscle damage after 50 and 100 drop jumps. A high-force, low intensity exercise protocol was used to avoid discrepancies regarding metabolic fatigue immediately after exercise. Healthy untrained men performed 50 ("50 group", n = 13) or 100 ("100 group", n = 13) intermittent (30-s interval between each jump) drop jumps, respectively, from the height of 0.5m with a counter-movement to a 90° knee flexion angle and immediate maximal rebound. Voluntary and electrically evoked knee extensor strength was assessed using an isokinetic dynamometer immediately before and at 2min after exercise, as well as 3, 7, and 14days after exercise. Creatine kinase (CK) activity and muscle soreness within 7days after exercise were also determined. The results showed that the decrease in voluntary isometric and isokinetic torque as well as 100Hz stimulation torque at the end of the 50 and 100 drop jumps was very similar, while substantial differences were found in low-frequency fatigue, shift in optimal knee joint angle, muscle soreness, and CK activity. In addition, there was slower muscle strength recovery after the 100 drop jumps. It is concluded that the predictive value of strength loss immediately after exercise as an indicator of muscle damage decreases as the jump number increases. Still, stimuli must be large enough for muscle torque to reach the reduction plateau. Therefore, magnitude of exercise becomes a major factor in accuracy of muscle damage predictions.

Low-Intensity Exercise Reverses Chronic Muscle Pain in the Rat in a Naloxone-Dependent Manner

Hoeger Bement MK, Sluka KA. Low-intensity exercise reverses chronic muscle pain in the rat in a naloxone-dependent manner. Objective To determine the effects of low-intensity exercise on chronic muscle pain and potential activation of the endogenous opioid system. Design Randomized placebo-controlled trial. Setting Animal laboratory. Animals Sixty-three male Sprague-Dawley rats. Interventions Rats performed a low-intensity exercise protocol for 5 consecutive days after the induction of chronic muscle pain. In a separate experiment, naloxone or saline was administered systemically before 5 low-intensity exercise sessions. Main Outcome Measure Mechanical hyperalgesia was measured using von Frey filaments to determine the mechanical withdrawal threshold. Results Low-intensity exercise increased mechanical withdrawal threshold in the chronic muscle pain model. Naloxone attenuated the antihyperalgesic effects of low-intensity exercise. Conclusions Low-intensity exercise reversed mechanical hyperalgesia in the chronic muscle pain model through activation of the endogenous opioid system.

Muscle fatigue, lactate, and pyruvate in mitochondrial myopathy with progressive external ophthalmoplegia

We studied muscle fatigue and serum lactate and pyruvate levels in 20 patients with mitochondrial myopathy with progressive external ophthalmoplegia (PEO). Fatigue was assessed in the adductor pollicis muscle (AP) using a low-intensity exercise protocol (20 min). Forces (TFs) and relaxation times of ulnar nerve evoked twitches, compound muscle action potentials (CMAPs), and maximal voluntary contractions (MVCs) were monitored. Serum lactate and pyruvate levels were independently measured at rest and after exercise on a bicycle (15 min, 30 W). Most patients showed abnormal fatigue of the AP with a reduction of TFs and MVCs and normal CMAPs. The reduced TFs were significantly correlated with lactate levels at rest (r= - 0.60, P<0.05) and less so with those after exercise (r=- 0.47,P<0.05). Pyruvate levels revealed a similar correlation although they were widely scattered. We conclude that abnormal fatigue in PEO is metabolic, is localized beyond the muscle fiber membrane, and involves the electrome-chanical coupling and the contractile apparatus. Serum lactate levels at rest are good predictors of fatigue in PEO.

Muscle fatigue, lactate, and pyruvate in mitochondrial myopathy with progressive external ophthalmoplegia

We studied muscle fatigue and serum lactate and pyruvate levels in 20 patients with mitochondrial myopathy with progressive external ophthalmoplegia (PEO). Fatigue was assessed in the adductor pollicis muscle (AP) using a low-intensity exercise protocol (20 min). Forces (TFs) and relaxation times of ulnar nerve evoked twitches, compound muscle action potentials (CMAPs), and maximal voluntary contractions (MVCs) were monitored. Serum lactate and pyruvate levels were independently measured at rest and after exercise on a bicycle (15 min, 30 W). Most patients showed abnormal fatigue of the AP with a reduction of TFs and MVCs and normal CMAPs. The reduced TFs were significantly correlated with lactate levels at rest (r = −0.60, P < 0.05) and less so with those after exercise (r = −0.47, P < 0.05). Pyruvate levels revealed a similar correlation although they were widely scattered. We conclude that abnormal fatigue in PEO is metabolic, is localized beyond the muscle fiber membrane, and involves the electromechanical coupling and the contractile apparatus. Serum lactate levels at rest are good predictors of fatigue in PEO. © 1996 John Wiley & Sons, Inc.

Angiotensin-converting enzyme inhibitors, left ventricular dysfunction, and early heart failure

A study was undertaken to examine the effects of the angiotensin-converting enzyme inhibitor lisinopril on exercise performance in 18 patients with major impairment of left ventricular systolic function. The study was a randomized, doubleblind, crossover design, and patients received treatment with either once-daily lisinopril (2.5–10 mg) or placebo for a period of 6 weeks. A total of 15 patients completed the study. Compared with placebo, lisinopril had no significant effect on supine or standing blood pressure or heart rate. Although lisinopril had no effect on exercise duration during a low-intensity exercise protocol, in patients undergoing a high-intensity exercise protocol, there was a trend toward improved exercise time and peak oxygen consumption improved significantly. In addition, treatment with lisinopril resulted in an increase in renal blood flow and a reduction in glomerular filtration rate. Moreover, administration of once-daily lisinopril 10 mg resulted in a decrease in plasma concentrations of angiotensin II, aldosterone, and atrial natriuretic peptide, and an increase in plasma concentrations of active renin.