ICU patients often suffer from rapid and severe muscle loss. It is not known if physical therapy can mitigate the muscle wasting associated with critical illness. The aim of this study is to investigate the effects of resistance exercise on muscle protein turnover in ICU patients. The investigators hypothesize that resistance exercise, in addition to amino acid supplementation and routine physiotherapy, results in an improved lower limb muscle protein balance compared to amino acid supplementation and routine physiotherapy alone.
Background The debilitating impact of critical illness has been recognized for several decades. Disability related to intensive care is now described as a syndrome called ICU-acquired weakness (ICUAW). ICUAW affects up to 70% of ICU patients and is most common with higher illness severity. Patients that develop ICUAW require longer hospitalization and have a higher risk of death. Weakness also has significant long-term consequences, and is associated with significant health care costs, delayed return to work, and overall poor quality of life. Preventing or reducing muscle atrophy is a potential way to counteract weakness. Critical illness is associated with a rapid loss of skeletal muscle. Studies in exercise physiology have demonstrated that resistance training and amino acid ingestion have synergistic effects on muscle protein synthesis in healthy subjects. It is therefore an appealing therapy to counteract muscle wasting in the ICU. Despite several clinical trials, there is equipoise regarding the efficacy of exercise in improving physical function in-ICU or after discharge. These mixed signals are unsurprising given the heterogeneous causes of ICUAW. Only a few studies in this field assess muscle architecture or cellular signaling in response to training. However, the gold standard in determining the anabolic response to exercise is to directly measure the effect on protein synthesis and breakdown. To our knowledge there is still no published research using this methodology to assess the effects of exercise interventions in critically ill patients. Aim and hypothesis The overall aim of this project is to determine the anabolic response to resistance exercise during critical illness. The investigators hypothesize that resistance exercise, in addition to amino acid supplementation and routine physiotherapy, results in an improved muscle protein balance in ICU patients compared to amino acid supplementation and routine physiotherapy alone (primary outcome). The effect of the intervention on other parameters of muscle protein kinetics and within-group differences in protein kinetics before and after physiotherapy will be assessed as secondary outcome measures.
Study Type
Patients in the intervention group will perform a seated knee extension exercise in three sets. Resistance will be adjusted using ankle weights, targeting 8-12 repetitions per set.
IV amino acids (Glavamin, Fresenius Kabi) delivered by continuous infusion at a rate of 0.1 g/kg/h. The infusion is started immediately prior to physiotherapy and continued until all blood samples required for outcome assessment are collected during a 90-minute resting period after the exercise session.
Karolinska University Hospital
Huddinge, Stockholm County, Sweden
Between-group difference in change in lower limb protein balance
The difference between the experimental and active comparator group in change in lower limb protein balance (nmol Phenylalanine/min) from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Between-group difference in change in lower limb protein synthesis
The difference between the experimental and active comparator group in change in lower limb protein synthesis (nmol Phenylalanine/min) from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Between-group difference in change in lower limb protein breakdown
The difference between the experimental and active comparator group in change in lower limb protein breakdown (nmol Phenylalanine/min) from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Between-group difference in change in lower limb 3-methylhistidine rate of appearance
The difference between the experimental and active comparator group in change in lower limb 3-methylhistidine rate of appearance (nmol 3-methylhistidine/min) from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
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INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
24
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein balance (experimental group)
The change in lower limb protein balance (nmol Phenylalanine/min) in the experimental group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein balance (active comparator group)
The change in lower limb protein balance (nmol Phenylalanine/min) in the active comparator group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein synthesis (experimental group)
The change in lower limb protein synthesis (nmol Phenylalanine/min) in the experimental group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein synthesis (active comparator group)
The change in lower limb protein synthesis (nmol Phenylalanine/min) in the active comparator group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein breakdown (experimental group)
The change in lower limb protein breakdown (nmol Phenylalanine/min) in the experimental group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb protein breakdown (active comparator group)
The change in lower limb protein breakdown (nmol Phenylalanine/min) in the active comparator group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb 3-methylhistidine rate of appearance (experimental group)
The change in lower limb 3-methylhistidine rate of appearance (nmol 3-methylhistidine/min) in the experimental group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.
Within-group change in lower limb 3-methylhistidine rate of appearance (active comparator group)
The change in lower limb 3-methylhistidine rate of appearance (nmol 3-methylhistidine/min) in the active comparator group, from baseline to post-physiotherapy. Blood samples and lower limb blood flow measurements to determine protein kinetics are performed at baseline (before IV amino acids and physiotherapy) and at 30, 60, and 90 minutes during bed rest after the physiotherapy session.
Time frame: Time = 165-180 minutes from start of study protocol to approximate Time = 315 minutes from start of study protocol.