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Jornal Vascular Brasileiro

versão impressa ISSN 1677-5449

J. vasc. bras. vol.12 no.2 Porto Alegre jun. 2013

http://dx.doi.org/10.1590/S1677-54492013000200004 

Original Articles

Effects of walking and strength training on walking capacity in individuals with claudication: meta-analysis

Alessandra de Souza Miranda1 

Lausanne Barreto de Carvalho Cahú Rodrigues1 

Sérgio Luiz Cahú Rodrigues1 

Crivaldo Gomes Cardoso Júnior2 

Maryela Oliveira Menacho3 

Diego Giulliano Destro Christofaro3 

Raphael Mendes Ritti-Dias1 

1Universidade de Pernambuco – UPE, Programa Associado de Pós-graduação em Educação Física, Recife, PE, Brazil.

2Universidade Estadual de Londrina – UEL, Centro de Educação Física e Desportos, Londrina, PR, Brazil.

3Universidade Estadual de Londrina – UEL, Centro de Ciências da Saúde, Londrina, PR, Brazil.

ABSTRACT

CONTEXT:

Over the past few years, several clinical trials have been performed to analyze the effects of exercise training on walking ability in patients with intermittent claudication (IC). However, it remains unclear which type of physical exercise provides the maximum benefits in terms of walking ability.

OBJECTIVE:

To analyze, by means of a meta-analysis, the effects of walking and strength training on the walking capacity in patients with IC.

METHODS:

Papers analyzing the effects of walking and strength training programs in patients with IC were browsed on the Medline, Lilacs, and Cochrane databases. Randomized clinical trials scoring >4 on the Physiotherapy Evidence Database (PEDro) scale and assessing claudication distance (CD) and total walking distance (TWD) were included in the review.

RESULTS:

Walking and strength training yielded increases in CD and TWD (P < 0.05). However, walking training yielded greater increases than strength training (P = 0.02).

CONCLUSION:

Walking and strength training improve walking capacity in patients with IC. However, greater improvements in TWD are obtained with walking training.

Key words: exercise; vascular diseases; peripheral arterial disease

INTRODUCTION

Peripheral artery disease (PAD), one of the main atherosclerotic diseases, is associated with high morbidity rates among the elderly1. The main symptom of PAD is intermittent claudication (IC), characterized by pain in the lower limbs, particularly the calf, when walking2. The prevalence of PAD is 3% to 10% in the general population and about 20% in the population older than 70 years3 , 4.

IC is the cause of limitations to walking, which may compromise the performance of physical activities of daily living5. In addition, individuals with IC have muscle atrophy and decreased muscle strength6, power and resistance in the lower limbs7. Supervised physical training combined with changes in life style has proven to be important interventions for the treatment of individuals with IC8, and significant increases in their walking ability and muscle and skeletal aptitudes have been found9 , 10.

Currently, there is evidence that supports the use of walking training in patients with PAD11. In fact, improvements in fitness and quality of life have been found, in addition to the fact that training is low cost and easy to perform12 - 14. Recent studies showed that strength training also improves fitness and quality of life of patients with PAD10 , 15 - 18. However, it is still unclear which of the two modalities of physical training results in greater increases in walking capacity.

This study conducted a meta-analysis to compare the effects of walking and strength training on the walking capacity of individuals with IC.

METHODS

Literature review

The MedLine, Lilacs and Cochrane databases were reviewed. First, studies were selected according to their publication date, which was limited to July 1980 to December 2010.

For the search, keywords in Portuguese and their corresponding keywords in English were selected using the DECS and the MeSH databases. The keywords selected were: exercício físico/physical exercise, aptidão física/fitness, caminhada/walking, treinamento de força/strength training and claudicação intermitente/intermittent claudication. For the selection of studies, combinations of keywords were used for the search. As a result, 1947 studies were retrieved, but only eight15 - 17 , 19 - 23 met inclusion criteria. Figure 1 shows the flowchart of study selection in this meta-analysis.

Figure 1 Flowchart of inclusion of studies in the meta-analysis CD - claudication distance; TWD - total walking distance. 

First, two authors read the study titles to check whether they met the purposes of this meta-analysis. When no decision was reached after reading the title, the abstract and later, if necessary, the whole study was read. This meta-analysis included studies that: (i) were randomized clinical trials; (ii) included a sample of individuals with PAD and symptoms of IC; (iii) analyzed the effects of supervised physical training (walking or strength); (iv) measured claudication distance (CD) or total walking distance (TWD) before and after the intervention; (v) included more than one experimental group; and (vi) had a score equal to or greater than 4 on the Physiotherapy Evidence Database (PEDro) scale, used to measure the quality of methods in clinical studies.

Data extraction

The following data were extracted from the studies that met inclusion criteria: (a) publication year; (b) groups; (c) number of individuals in each group; (d) type of physical exercises; (e) duration of intervention; (f) frequency (times a week); (g) volume of training session; (h) method used to measure intensity; (i) intensity prescribed; (j) initial CD or TWD; (k) final CD or TWD.

Data analysis

Mean and standard deviation values were calculated according to mean values in the studies to describe the characteristics of individuals included in the study. For inferential analysis, mean difference and 95% confidence intervals were calculated; the fixed effects model was used when results were homogeneous (P < 0.10); and a random effects model was used when results were heterogeneous (P < 0.10). The Review Manager 5.1 software was used for all analyses.

RESULTS

Study quality

Mean PEDro score of the studies included was 5.5 ± 0.9, and scores ranged from 4 to 7 (Table 1). The factors that lowered scores in a relevant way were: participant distribution was not blinded15 - 17 , 20 , 22 , 23; participant assignment to intervention groups was not blinded15 - 17 , 19 - 23; the individuals that administered the training program were not blinded15 - 17 , 19 - 23; and statistical analysis did not follow intention to treat15 - 17 , 19 - 23.

Table 1 Quality of studies included in meta-analysis.  

Study Score
Crowther19 5/10
Hiatt15 5/10
McDermott16 7/10
Mika20 6/10
Parr23 4/10
Ritti-Dias17 6/10
Sanderson21 6/10
Tsai22 5/10

Study characteristics

Of a total of 424 individuals included, 238 underwent physical training (Table 2). Most participants were men (65%) and elderly (67 ± 4 years). The duration of PAD described in four studies15 , 20 , 22 , 23 was 3.4 ± 0.8 years. All individuals included in the study had mild to moderate IC, and mean ankle-brachial index (ABI) was 0.64 ± 0.06.

Table 2 Characteristics of the studies that met inclusion criteria.  

Study Intervention Subjects (n) Duration (weeks) Frequency (week)
Crowther19 Treadmill walking 10 48 3
Control 11 48 -
Hiatt15 Strength 9 12 3
Treadmill walking 10 12 3
Control 10 12 -
McDemort16 Strength 52 24 3
Treadmill walking 51 24 3
Mika20 Treadmill walking 27 12 3
Control 28 12 -
Parr23 Strength 9 6 3
Control 8 6 -
Ritti-Dias17 Strength 15 12 2
Treadmill walking 15 12 2
Sanderson21 Treadmill walking 13 6 3
Control 14 6 -
Tsai22 Treadmill walking 27 12 3
Control 26 12 -

Body mass (BM) was described in four studies15 , 19 , 21 , 23, and mean BM was 76.0 ± 4.9 kg; body mass index (BMI) was found in three studies16 , 19 , 23, and mean BMI was 28.6 ± 2.0 kg/m2. The analysis of comorbidities revealed that four studies15 , 17 , 19 , 22 described the presence of hypertension, five15 , 17 , 19 , 21 , 22, heart disease, four16 , 17 , 19 , 21, diabetes, and two15 , 22, dyslipidemia. In addition, most studies15 - 17 , 19 - 22 reported that individuals were smokers.

Walking ability before intervention

CD was reported in eight studies15 - 17 , 19 - 23. Mean CD before intervention was 203 ± 126m and 197 ± 124m in the studies that used walking and strength training. In all studies, CD was similar between experimental and control groups before intervention.

Mean TWD before intervention was 365 ± 182 m and 329 ± 171m in the studies that used walking and strength training. In all studies, TWD was similar between experimental and control groups before intervention.

Training program

Duration ranged from six23 to 4819 weeks, and 12 weeks was the most frequent duration15 , 17 , 20 , 22. Frequency ranged from two17 to three times a week15 - 17 , 19 - 23, whereas session length ranged from 20 to 60 minutes15 - 17 , 19 - 23.

Walking training was prescribed according to perception of exertion, with Borg scores ranging from 11 to 1416 , 17, and perception of claudication pain, with scores ranging from 3 to 419. Peak oxygen consumption (peak VO2) was used in one study, at an intensity of 80% of peak VO2 21 .

Strength training was prescribed according to perception of exertion, with Borg scores ranging from 11 to 1316 , 17, and tests of 615 and 1523 maximum repetitions.

Effects of training on walking ability

The comparison of the effects of walking training and control intervention on CD (Table 3) revealed that only walking training significantly increased CD (152 m; 95% CI [135, 168], P < 0.00001). The comparison of the effects of strength training and control intervention on CD revealed that only strength training significantly increased CD (17 m; 95% CI [-27, 61], P = 0.03). The comparison of increases of CD in walking and strength training revealed that the effects of the two trainings were similar (P = 0.32).

Table 3 Effects of walking and strength training on claudication distance.  

Study Mean SD Total Mean SD Total Weight Mean difference IV, fixed, 95%CI Mean difference IV, fixed, 95% CI
Control vs. walking training
Hiatt 1994 354 227 10 164 69 10 1.3% 190 [43, 337]
McDermott 2009 291 170 51 194 169 53 6.7% 97 [32, 162]
Mika 2006 340 53 41 185 25 39 87.7% 155 [137, 173]
Sanderson 2006 455 276 13 334 331 14 0.5% 121 [-108, 350]
Tsai 2002 327 143 27 169 180 26 3.7% 158 [70, 246]
Total (95%CI) 142 142 100% 152 [135, 168]
Heterogeneity: X2 = 3.18 df = 4 (P = 0.53); I2 = 0%
Total effects test: Z = 17.59 (P < 0.00001)
Control vs. strength training
Hiatt 1994 153 58 10 163 68 10 63,2% -10 [-65, 45]
McDermott 2009 269 138 27 193 169 26 28,0% 76 [-7, 159]
Parr 2009 202 175 9 175 136 8 8,8% 27 [-121, 175]
Total (95%CI) 46 44 100% 17 [-27, 61]
Heterogeneity: X2 = 1.94 df = 4 (P = 0.16); I2 = 48%
Total effects test: Z = 2.18 (P = 0.03)
Strength training vs. walking training
Hiatt 1994 354 227 10 153 58 9 29,9% 201 [55, 347]
McDermott 2009 291 170 51 269 138 52 46,2% 22 [-38, 82]
Ritti-Dias 2010 469 237 15 504 276 15 23,9% -35 [-219, 149]
Total (95%CI) 76 76 100% 62 [-60, 184]
Heterogeneity: Tau2 = 7469.79 X2 = 5.67 df = 2 (P = 0.06); I2 = 65%
Total effects test: Z = 0.99 (P = 0.32)

The comparison of the effects of walking training and control intervention on TWD15 , 16 , 20 - 22 (Table 4) revealed that only walking training significantly increased TWD (173 m; 95% CI [56, 290], P < 0.00001). Also, the comparison of the effects of strength training and control intervention on TWD revealed that only strength training significantly increased TWD (106 m; 95% CI [33, 180] P=0.005). However, the increase in TWD as a result of walking training was greater (P=0.02) than that obtained after strength training.

Table 4 Effects of walking and strength training on total walking distance.  

Study Mean SD Total Mean SD Total Weight Mean difference IV, fixed, 95%CI Mean difference IV, fixed, 95%CI
Control vs. walking training
Crowther 2008 650 273 10 1,039 361 11 11.3% -389 [-661, -117]
Hiatt 1994 776 385 10 385 142 10 12.3% 391 [137, 645]
Mc Dermott 2009 612 211 51 380 294 53 24.2% 232 [134, 330]
Mika 2006 577 69 41 396 67 39 28.7% 181 [151, 211]
Tsai 2002 660 195 27 401 200 26 23.5% 259 [153, 365]
Total (95%CI) 139 139 100% 173 [56, 290]
Heterogeneity: Tau2 = 12207.84 X2 = 22.38 df = 4 (P = 0.0002); I2 = 82%
Total effects test: Z = 2.90 (P = 0.004)
Control vs. strength training
Hiatt 1994 448 275 9 385 143 10 13.5% 63 [-137, 263]
McDermott 2009 504 214 52 380 212 53 81.3% 124 [43, 205]
Parr 2009 399 186 9 460 430 8 5.2% -61 [-383, 261]
Total (95%CI) 70 71 100% 106 [33, 180]
Heterogeneity: X2 = 1.40 df = 2 (P = 0.53); I2 = 0%
Total effects test: Z = 2.83 (P = 0.005)
Strength training vs. walking training
Hiatt 1994 776 385 10 448 275 9 8.5% 328 [29, 627]
McDermott 2009 612 294 51 504 214 52 76.4% 108 [9, 207]
Ritti-Dias 2010 721 289 15 775 334 15 15.1% -54 [-278, 170]
Total (95%CI) 76 76 100% 102 [15, 189]
Heterogeneity: X2 = 4.08 df = 2 (P = 0.13); I2 = 51%
Total effects test: Z = 0.99 (P = 0.32)

DISCUSSION

This study compared the effects of walking training and strength training on the walking capacity of individuals with IC using data in the literature. For that purpose, a meta-analysis was conducted. Results showed that: (i) walking and strength training increased the walking capacity of patients with IC; (ii) the effects of strength and walking training on CD are similar; (iii) walking training resulted in greater TWD increases than strength training.

Most studies included in this meta-analysis used walking training15 - 17 , 19 - 22. This may be partly explained by the fact that several Vascular Surgery Associations8 , 11, in their official guidelines, recommend walking as the most important exercise for patients with PAD. Recent recommendations have included strength training as part of training for individuals with PAD, although only a few studies using strength training have been published. In fact, our analysis included only four studies that evaluated the effects of strength training on the walking ability of patients with PAD15 - 17 , 23. Furthermore, one of these studies had a weight greater than 70% in the meta-analysis because of the high number of individual included in its sample. Therefore, further studies about this topic should be conducted.

The effects of walking and strength training on CD were similar, but TWD increased more after walking training. This can be explained by the fact that the mechanisms of increase in walking ability differ between walking and strength training. The increases in walking ability after walking training have been assigned to: angiogenesis24; improvement of endothelial function; increase of oxidative enzyme concentrations13; and improvement of walking efficiency. In contrast, the increases obtained with strength training have been basically assigned to angiogenesis and improvements on walking efficiency. Therefore, the effects of walking training on oxidative metabolism seem to explain the differences between the effects of walking and strength training on the walking ability of patients with PAD.

One of the limitations of this study was the inclusion of studies only in Portuguese or English. Another important aspect was the fact that, although only studies that measured walking ability using treadmills were included, there was some variation in the protocols used. Therefore, results between studies should be compared cautiously. However, individual studies used the same protocol to measure walking ability, and we were, therefore, able to assess the effects of training between groups.

CONCLUSION

Walking and strength training improve the walking capacity of patients with PAD, but walking training results in greater increases of TWD.

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Financial support: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE).

The study was carried out at Universidade de Pernambuco.

Author contributions

Conception and design: RMRD, ASM, LBCCR, SLCR

Analysis and interpretation: RMR, CGCJ, DGDC, MOM

Data collection: ASM, LBCCR

Writing the article: RMRD, ASM

Critical revision of the article: LABCR, CGCJ, SLCR, DGDC, MOM

Final approval of the article*: ASM, LBCCR, SLCR, CGCJ, MOM, DGDC, RR

Statistical analysis: DGDC, MOM

Overall responsibility: RMRD

Received: July 16, 2012; Accepted: December 21, 2012

ASM, LBCCR holds a MSc degree from Universidade de Pernambuco (UPE).

SLCR is a PhD candidate at Graduate Program in Physical Education, UPE/UFPB.

CGC holds a PhD degree from Universidade de São Paulo (USP).

MOM holds a MSc degree from Universidade Estadual de Londrina (UEL).

DGDC holds a PhD degree from Universidade Estadual de Londrina (UEL)

RMR holds a PhD degree from Universidade de São Paulo (USP).

Conflicts of interest: No conflicts of interest declared concerning the publication of this article.

*All authors should have read and approved of the final version of the article submitted to J Vasc Bras.

Correspondence Raphael Mendes Ritti Dias ESEF-UPE Rua Arnóbio Marques, 310, Santo Amaro CEP 50100-130 - Recife (PE), Brazil Fone: (81) 3183-3375/(81) 9728-6878 E-mail: raphaelritti@gmail.com

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