Physical performance (PP) and functional balance (FB) abnormalities are frequently encountered problems in patients on maintenance renal hemodialysis (MRH). Although the exercise therapy is an adjunctive to the routine medical care for patients with chronic kidney disease of various stages; but the benefits as well as the long-term effects of different exercises on the PP and FB in patients on MRH are not yet fully described. In this study; Sixty-six patients on MRH (36 males, 30 females), age 35–45 years, were randomly assigned into one of the three groups: aerobic exercise training group (AETG), resistance exercise training group (RETG), and control group (CG). The PP (evaluated using the 6-min walk test “6MWT”) and the FB (evaluated via the Berg balance scale “BBS”) were the main study outcomes evaluated prestudy (evaluation-1), after 3 months (evaluation-2) and 2 months poststudy cessation (evaluation-3). Results revealed that the PP and FB mean values and percentages of changes at evaluation-2 were 444.25±21.83 (33.1%), 413.57±28.55 (22.52%), 337±12.23 (0.33%) m, 50.05±0.89 (22.95%), 49.95±2.06 (22.52%), 41.28±1.75 (0.94%) for AETG, RETG, and CG respectively. At evaluation-3; the PP and FB mean values and the percentage of changes were 425±21.49 (27.36), 366.86±17.47 (8.5%), 336.68 (0.42%) m, 44.4±1.85 (8.06%), 42.95±2.04 (5.003%), 39.48±2.06 (−4.44%) for AETG, RETG, and CG respectively. In conclusions; both aerobic exercise training (AET) and resistance exercise training (RET) have favorable effects, with the AET has higher short and long-term favorable effects on the PP and FB than RET in patients on MRH.
Chronic kidney disease (CKD) is an alarming health problem affecting millions of people worldwide, (
Patients with CKD are generally suffering reduced activity level (
Easy fatigability, altered physical performance (PP) (
Effective strategies are required to modify the cardiovascular risk factors that are commonly encountered in patients on MRH (
In spite of the continuously expanding body of knowledge regarding the benefits of exercise training in patients on MRH; further investigations are required to fully clarify the effects of exercise training in those patients (
Eighty-Seven eligible volunteer patients on MRH were recruited to be enrolled in this study. Twenty-one patients were withdrawn and excluded before randomization and group allocation. The remaining 66 patients (36 males: 30 females) participated and completed this study (
All participants underwent the same battery of tests, were fully aware of the study goals and procedures, agreed to participate in this study and signed written informed consent at the beginning of this study that was carried out between May 2017 and November 2018, according to the principles of the Declaration of Helsinki 1975, revised Hong Kong 1989 and was approved by the institutional ethics committee of the Faculty of Physical Therapy, Cairo University (approval number No: P.T.REC/012/002123).
The nature of the study did not allow full blinding except for the evaluator and the data manager. After medical screening; 66 eligible patients were randomly allocated (using a computer program SAS Proc Plan; SAS Institute Cary NC, USA) into one of the three groups: the aerobic exercise training group (AETG; n= 20), the resistance exercise training group (RETG; n=21), and the control group (CG; n=25). All participants were encouraged to stabilize their medical treatment and the dialysis regimen throughout the study.
The primary variables were the PP (evaluated using the 6-min walk test “6MWT”) in meter, and the FB (evaluated using the Berg balance scale “BBS”). Each variable was evaluated at 3 time-points throughout the study: prestudy (evaluation-1), after 3 months (evaluation-2) and 2 months poststudy cessation (evaluation-3). Demographic characteristics including weight, height and BMI were assessed using portable stadiometer (Detecto’s ProMed 6129 medical scale, 203 E. Daugherty, Webb City, MO, USA). Resting heart rate (HR rest), systolic and diastolic blood pressure were evaluated from non-fistula arm using digital sphygmomanometer; (BTL CardioPoint ABPM apparatus “BTL Science and Technology [Shenzhen] Co., Ltd, China”) following established guidelines (
Maximum heart rate (HRmax) was assessed through the modified symptom-limited Bruce exercise testing protocol using a standard stress testing instrument, (Cardiac Science Quinton Q-Stress Test system, Cardiac Science International A/S, Kirke Vaerloesevej 14, DK-3500 Vaerloese, Dänemark) following established guidelines (
After proper explanation of the test procedure; evaluation of PP was performed using the 6MWT. Following previously published guidelines (
The FB was evaluated using the “BBS”, consisted of 14 items, each item score ranges from zero (the lowest level of function) to four where (the highest level of performance). Activities performed in the BBS varied in difficulty from setting, to standing, to standing on one leg. The used materials included standard chairs (one with arm rests, one without), 15 ft walkway, a stopwatch, a step and a ruler. Participant was asked to follow instructions in maintaining their balance while holding on certain position for specified time or achieving the requested task. The FB evaluations and data collection were done by the same examiner following standard guidelines (
Each patient adhered to his/her prescribed training program; no serious abnormalities were recorded throughout the study.
Each participant in this group (n=20) received twelve weeks of gradually progressive aerobic exercise training (AET) three times/week, on the nondialysis day’s session schedule. Sufficient time (2–3 hours) was allowed after the breakfast before starting the session to avoid hypoglycemia.
After conducting a preliminary session to familiarize the patients on the treadmill and ensure safety measures during training; each session started and ended with 5 to 10 min warm-up/cool-down in the form of quite walking on the treadmill at intensity of 50% HRmax. The exercise training intensity was closely monitored using the wireless pulse oximeter (IN-C013 China Rechargeable Handheld CMS 50I Contec Ear Fingertip Pulse Oximeter, ICEN Technology Company Limited, Amydimed, Guangdong, China) worn by the patient and via the 15 points Borge’s scale of perceived exertion.
The duration and intensity of the AET were gradually adjusted at regular intervals. The training duration started with 30 min and gradually increased to reach 45 min at the end of the study. The training intensity started with 55% HRmax, reached 70% HRmax at the end of the study (
The closely supervised resistance training was conducted 3 times weekly for 12 weeks. The program consisted of leg curl and leg extension exercises using Kettler 7752-800 multigym machine, EMS Physio (UK). Each session was preceded and followed by a warm-up/cool down phase typically as for the AETG.
The resistance training was conducted following previously published guidelines (
Twenty-five participants were directed to maintain their regular medical care and their usual physical activity throughout the study but did not participate in any exercise training.
Data analysis was performed using IBM SPSS Statistics ver. 20.0 (IBM Co., Armonk, NY, USA) data are presented as mean and standard deviations. The Kolmogorov–Smirnov test was conducted to test data normal distribution. Changes in the PP and the FB mean values within and between groups at the three evaluation points were analyzed using the repeated measures analysis of variance with pairwise comparisons, with two “within-subjects” factors; treatment (AET, RET, control) and time (evaluation-1, evaluation-2, evaluation-3) to test hypothesis within and between groups. The level of significance was set at
Eighty-Seven patients were recruited to participate in this study, only 66 participants enrolled and completed the study and were randomly allocated to either the AETG (n=20), RETG (n=21), or CG (n=25) (
Results revealed that there were significant increases in mean values of PP by 33.1%, 22.52% and FB by 22.95%, 22.25% for the AETG and the RETG groups, respectively (
Within the group’s comparison between the evaluation-2 and −3 time points revealed that there were significant reduction in the mean values of the PP by 4.33%, 10.93% and the FB by 11.29%, 13.98% for the AETG and the RETG groups, respectively (
Results revealed that there were non-significant differences in the PP (
Results revealed that there were significant differences in the PP and the FB mean values, but in favor of the AETG group (
The results of this study confirmed the importance of applying regular aerobic as well as strength training in patients on MRH. Aerobic as well as strength training proved to have favorable short and long-term effects on the PP and the FB in patients on MRH. The current study investigated short as well as long-term responses of the PP and the FB to exercise therapy in patients on MRH.
Factors led to the reduction of physical activity level in patients on regular MRH include decreased muscle strength (
Investigating the effects of resistance exercise training gained relatively lesser attention than that of AET in patients on MRH, furthermore; the majority of these investigations evaluated the short-term effects of training and were done during the hemodialysis sessions. Despite its proven benefits; exercise training in patients on MRH is rarely conducted on a regular basis (
The significant increases in the PP and the FB in patients on MRH in this study are comparable to results reported in previous studies. Patients on regular MRH are usually suffering reduced work capacity that can be efficiently improved by exercise practice (
The significant increase in the PP in response to exercise training is mainly represented in shortening the time required to perform functional tasks in patients on MRH and can be attributed to increased muscular endurance (
Earlier studies reported that CKD is associated with progressive loss of strength in the large body muscles (
Some limitations were encountered in the current study. Efforts were done to avoid bias and to optimize blinding, but the nature of the study limits the double blinding process since both patients and physiotherapist should know the group allocation and the type of the exercise training. Absence of combined aerobic plus strength exercise training group, relatively short follow-up duration are additional limitations. Future studies should try to overcome these limitations. In conclusion; both AET and RET have extended favorable effects on the PP and FB in patients on MRH. The AET showed higher short and long-term favorable effects than the RET on the PP and FB in patients on MRH. So the AET is still the recommended approach to improve the PP and FB in patients on MRH.
No potential conflict of interest relevant to this article was reported.
Patient’s flowchart.
Mean values of the physical performance in all groups. AETG, aerobic exercise training group; RETG, resistance exercise training group; CG, control group.
Mean values of functional balance in all groups. AETG, aerobic exercise training group; RETG, resistance exercise training group; CG, control group.
The parameters of the aerobic and resistance exercise training programs
Training | Weeks | Duration | Intensity |
---|---|---|---|
Aerobic training | 1–3 | 30 min | 55% HRmax |
4–6 | 35 min | 60% HRmax | |
7–9 | 40 min | 65% HRmax | |
10–12 | 45 min | 70% HRmax | |
| |||
Resistance training | 1–2 | Two sets of 8 repetitions 70% 1RM | |
3–4 | Three sets of 8 repetitions 70% 1RM | ||
5–6 | Two sets of 9 repetitions 70% 1RM | ||
7–8 | Three sets of 9 repetitions 70% 1RM | ||
9–10 | Two sets of 10 repetitions 70% 1RM | ||
11–12 | Three sets of 10 repetitions 70% 1RM |
HRmax, maximum heart rate; 1RM, one-repetition maximum.
The demographic characteristics of participants of all groups
Variable | AETG (n=20) | REG (n=21) | CG (n= 25) | ||
---|---|---|---|---|---|
Age (yr) | 39.9±3.75 | 39.67±4.07 | 40.12±2.86 | 0.09 | 0.91** |
| |||||
Weight (kg) | 76.35±7.98 | 75.81±9.47 | 75.88±7.06 | 0.03 | 0.97** |
| |||||
Height (m) | 1.68±0.09 | 1.67±0.1 | 1.68±0.08 | 0.16 | 0.85** |
| |||||
BMI (kg/m2) | 27.07±2.62 | 27.32±2.68 | 27.17±3.28 | 0.40 | 0.96** |
| |||||
SBP (mmHg) | 145.3±2.58 | 144.76±2.79 | 145.64±2.78 | 0.60 | 0.55** |
| |||||
DBP (mmHg) | 93.1±1.12 | 92.95±1.57 | 92.92±1.71 | 0.90 | 0.92** |
| |||||
Length of the hemodialysis vintage (mo) | 38.3±8.13 | 37.86±8.77 | 38.16±7.26 | 0.02 | 0.98** |
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Hours of dialysis/wk | 14.5±3.05 | 14.67±2.61 | 15.04±2.32 | 0.25 | 0.78** |
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HRmax (beat/min) | 151.55±3.28 | 151.24±3.77 | 150.6±3.42 | 0.44 | 0.65** |
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CKD etiology (%) | |||||
Hypertension | 7 | 6 | 9 | ||
Glomerul-onephritis | 8 | 10 | 9 | ||
Unknown/others | 5 | 5 | 7 | ||
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Smoking history | |||||
Smoker:ex-smoker:nonsmoker | 5:9:6 | 7:8:6 | 7:12:6 | ||
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Gender | |||||
Female:male | 10:10 | 11:10 | 15:10 |
AETG, aerobic exercise training group; REG, resistance exercise training group; CG, control group; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HRmax, maximum heart rate; CDK, chronic kidney disease.
Physical performance and functional balance of all groups
AETG (n=20) | RETG (n=21) | CG (n=25) | |||||||
---|---|---|---|---|---|---|---|---|---|
|
|
| |||||||
Eval-1 | Eval-2 | Eval-3 | Eval-1 | Eval-2 | Eval-3 | Eval-1 | Eval-2 | Eval-3 | |
Physical performance (m) | |||||||||
Mean±SD | 334.1±14.16 | 444.25±21.83 | 425±21.49 | 338.38±14.12 | 413.57±28.55 | 366.86±17.47 | 338.08±10.69 | 337±12.23 | 336.68±11.38 |
|
256.78 (<0.01 |
||||||||
502.1 (<0.01 |
94.05 (<0.01 |
1.97 (0.17**) | |||||||
168.49 (<0.01 |
45.003 (<0.01 |
0.27 (0.61**) | |||||||
392.48 (<0.01 |
70.74 (<0.01 |
2.39 (0.1**) | |||||||
| |||||||||
Functional balance | |||||||||
Mean±SD | 41.15±2.35 | 50.05±0.89 | 44.4±1.85 | 40.95±2.25 | 49.95±2.06 | 42.95±2.04 | 41.36±2.22 | 41.28±1.75 | 39.48±2.06 |
|
381.44 (<0.05 |
||||||||
342.82 (<0.01 |
274.36 (<0.05 |
0.1 (0.76**) | |||||||
222.38 (<0.01 |
381.11 (<0.05 |
40.5 (0.06**) | |||||||
231.11 (<0.01 |
240.51 (<0.01 |
23.87 (0.07**) |
AETG, aerobic exercise training group; RETG, resistance exercise training group; CG, control group; Eval, evaluation; SD, standard deviation.
Degree of freedom=2, 62.
Between-groups comparison of physical performance and functional balance (
Prestudy(Eval-1) | After 12 weeks (Eval-2) | Eight weeks poststudy (Eval-3) | |
---|---|---|---|
Physical performance | 0.71, 0.5** | 152.1, <0.01 |
153.81, <0.01 |
Functional balance | 0.19, 0.83** | 215.11, <0.01 |
36.87, <0.01 |
Eval, evaluation.