ISSN : 1598-2939
The purpose of this study was to differences in cardiovascular risk factors and upper and lower limb muscle function according to the WHR classification in women with obese. Eighty-three obese women with over 30% body fat who aged between 20- and 30-years were divided into 3 groups: normal control group (NCG, n=6), obese women with low WHR group (WHR 0.85 or less+ more than 30% body fat, OLW, n=64), obese women with high WHR group (WHR 0.85 or more+ more than 30% body fat, OHW, n=13). We performed measurements to determine cardiovascular risk factors, basic physical fitness, isokinetic knee and trunk muscle functions according to WHR classification.
As the result of this study, the knee flexor peak torque and hamstring to quadriceps torque ratio (H:Q ratio) as well as isokinetic endurance capacity of the right and left knee flexors were significantly higher in the NCG compared to the OLW and OHW. In addition, sergeant jump was significantly higher in the NCG compared to the OLW and OHW. But other basic physical fitness factors and cardiovascular disease risk factors were no significant difference between all groups. Our findings confirmed that WHR risk level may be an important predictor of lower extremity muscle function in obese women.
The purpose of this study was to differences in cardiovascular risk factors and upper and lower limb muscle function according to the WHR classification in women with obese. Eighty-three obese women with over 30% body fat who aged between 20- and 30-years were divided into 3 groups: normal control group (NCG, n=6), obese women with low WHR group (WHR 0.85 or less+ more than 30% body fat, OLW, n=64), obese women with high WHR group (WHR 0.85 or more+ more than 30% body fat, OHW, n=13). We performed measurements to determine cardiovascular risk factors, basic physical fitness, isokinetic knee and trunk muscle functions according to WHR classification.
As the result of this study, the knee flexor peak torque and hamstring to quadriceps torque ratio (H:Q ratio) as well as isokinetic endurance capacity of the right and left knee flexors were significantly higher in the NCG compared to the OLW and OHW. In addition, sergeant jump was significantly higher in the NCG compared to the OLW and OHW. But other basic physical fitness factors and cardiovascular disease risk factors were no significant difference between all groups. Our findings confirmed that WHR risk level may be an important predictor of lower extremity muscle function in obese women.
Obesity has been known to be one of the most important risk factors for inducing myocardial infarction, angina pectoris, and hypertension (Romero-Corral et al., 2006), suggesting that the diagnosis and evaluation of obesity are essential for a healthy life in modern people (Flegal et al., 2016).
Obese is categorized in various measurement index, which include body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), and body fat percentage(%BF). In clinical practice, the BMI is the most common method for diagnosing obesity, which was based on a person's weight in kilograms and height in meters. The Korea medical community has classified 18.6 and 22.9 kg/m2 as normal BMI, 23 to 24.9 kg/m2 as overweight, and 25 kg/m2 and more as obese according to the Asia-Pacific criteria. However, as the obesity prediction methods by BMI has limitations in classifying obesity with high body fat mass and overweight with high muscle mass, the importance of classifying obesity using WHR has recently been emphasized (Lee et al., 2008). In a precious study of Janssen et al. (2002) that reported an association between WHR and obesity, an increase in abdominal adiposity had a more direct influence on cardiovascular disease than an increase in fat mass in other body parts. In addition, Schneider et al. (2010) suggested that WC and WHR were more accurate than BMI as predictive indicators of abdominal obesity in a study of 6355 obese subjects.
The world health organization (WHO) has provided guidelines for the optimal criteria for WHR to be 0.85 or less for women and 0.9 or less for men, because the women usually concentrate body fat mass on the hip and men accumulated on the waist. A WHR value of 1.0 or higher can induce cardiovascular and metabolic diseases as well as various complications related to obesity (Elsayed et al., 2008). In the field of exercise physiology studied on relationship between WHR and physical fitness in obese people, Correa-Rodríguez et al. (2018) provided some information that WHR and physical fitness have a high correlation and may be predictors of hypertension, diabetes, and cardiovascular diseases.
Recent studies have reported that obese people with high maximal oxygen uptake (VO2max) have low WC and WHR, and show high physical fitness in push-ups, sit-up and vertical jump (Ekblom-Bak et al., 2009; Ortega et al., 2019; Ross & Katzmarzyk, 2003). But Lockie et al. (2020) highlighted that WC is most important indicator in predicting obesity because the physical fitness of obese people is further closely related to WC compared to WHR. To date, these previous studies reporting on physical fitness and WHR in obese are not clear. Therefore, it is necessary to confirm the relationship between physical fitness and cardiovascular disease based on WHR criteria in obese women. The purpose of this study was to investigate differences in cardiovascular disease risk factors and upper and lower limb muscle function according to the WHR classification in women with obese.
The participants of this study were 87 adult women who did not have cardiovascular and musculoskeletal diseases and food allergies within the last six months. Eighty-thirty participants, excluding 4 subjects with health problem, were included in this analysis. And they were randomly classified into normal control group (NCG, n=6), obese women with low WHR group (WHR 0.85 or less+ more than 30% body fat, OLW, n=64), obese women with high WHR group (WHR 0.85 or more+ more than 30% body fat, OHW, n=13). Participant characteristics was explained in Table 1.
Height and weight were measured in light clothing using height and weight scale (DS-103M, Dong San Jenix, Seoul, Korea), and body composition was analysed by Inbody 770 (Inbody 770, Inbody, Seoul, Korea). Waist circumference was measured midway between the lower rib margin and iliac crest. Hip circumference was measured at widest circumference over the greater trochanters.
Cardiovascular disease risk factors including blood pressure, fasting glucose (FG) and blood lipid were analysed. Fasting glucose was examined by Accu-Chek® Guide (Roche, Mannheim, Germany) and total cholesterol (TC), triglyceride (TG), High-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured using by mission cholesterol meter (Mission Cholesterol Meter, Acon Laboratories, Inc. San Diego, CA). Blood pressure was measured using blood pressure device (BPBIO330, InBody, Korea) after taking a rest for 30 min.
Basic physical fitness consisted of grip strength (T.K.K.-5101, TAKEI, Japan), back strength (T.K.K. 5402, TAKEI, Japan), sit-up (T.K.K.-5505, TAKEI, Japan), sit and reach (T.K.K. 5111, Takei, Japan), sergeant jump (DW 771A, SKARO, Korea), and sit-to-stand (Martinez-Hernandez & Dehghani-Sanij, 2019). Physical efficiency index (PEI) was determined by the equations (100 x test duration in seconds) divided by (2 x sum of heart beats in the recovery periods) after the Harvard step test for 5min.
The isokinetic muscle functions of the trunk (load speed 30°/sec) and knee (load speed 60°/sec and 240°/sec) were measured using isokinetic device (Humac Norm 776, CSMI, Boston, USA). The maximum isokinetic trunk strength was measured 3 times at 30°/sec. The isokinetic knee strength and endurance tests on hamstring and quadriceps muscles was repeated 3 times at 60°/sec and 12 times at 240/sec, respectively. The range of the motion (ROM) of the trunk during the tests were set from −10° to 70° and ROM of the knee ranged from 0° to 90°. All isokinetic variables were presented in absolute and relative values.
The mean and standard deviation of all variables were calculated using IBM SPSS Statistics statistical program (Version 24.0; SPSS, Inc., Chicago, IL, USA). To confirm the difference of between groups was performed using one-way analysis of variance followed by Scheffe post hoc test. The significance level was set at p<0.05.
The WHR, BMI and FFM have been known as an important maker for diagnosing obesity. As shown in Table 2. But FFM (F=.321, p=.726) was no significant difference among groups. BMI (F=4.670, p=.012) was significant differences between groups. BMI were significantly higher in the OHW compared to those in the NCG.
To examine the relationship between comparison of cardiovascular disease risk factors according to WHR classification, we investigated blood pressure, blood lipids and fasting glucose. As shown in table 3, TC (F=1.119, p=.332), TG (F=1.625, p=.203), HDL-C (F=.259, p=.772), LDL-C (F=1.025, p=.364), FG (F=.665, p=.517) and SBP (F=1.554, p=.218) were no significant difference between group. But DBP (F=6.528, p=.002) showed a significant difference among groups, suggesting that DBP might be increased in obese women with high WHR values compared to the NCG and OLW.
As a result of basic physical fitness according to WHR classification, grip (F=.497, p=.610) and back strength (F=.436, p=.648), sit-up (F=.231, p=.794), sit and reach (F=.313, p=.732), PEI (F=.745, p=.478), trunk back extension (F=.422, p=.657) and sit to stand (F=.138, p=.871) were no significant difference among groups. But sergeant jump showed a significant difference among groups (F=.7.282, p=.001), suggesting that obese people, regardless of abdominal adiposity, have lower power capacity than the normal people (Table 4).
We performed isokinetic knee flexion and extension test at 60° and 240°/sec, and isokinetic trunk flexion and extension test were measured at the 30°/sec for identifying maximum strength, endurance, and dynamic balance in obese women according to WHR classification. As shown in table 5. Absolute peak flexor torque (F=3.087, p=.051) and hamstring and quadriceps (H:Q) ratio in the right knee (F=3.983, p=.022) were significant difference among groups. In the result of post-hoc, absolute flexion peak torque for the right knee was higher in the NCG than those in the OHW, and H:Q ratio for the right was significantly lower the OLW and OHW compared to the NCG. However, there was no significant difference in other variables in isokinetic knee test at the 60°/sec. At 240°/sec, absolute peak flexor torque of the right and left knee (F=3.087, p=.051) were significant difference among groups. In the result of post-hoc, absolute flexion peak torque for the right knee was significantly higher the NCG compared to those in the OHW. But flexion peak torque for the left knee was higher the NCG compared to those in the OLW. There was no significant difference in other variables in isokinetic trunk test at the 30°/sec.
For decades, percent body fat and BMI has been widely used as an important marker of obesity in daily life and the medical community. But recently WHR or WHtR are found to be a clear indicator for diagnosing obesity (Pischon et al., 2008). In this study, we confirmed differences in body composition according to WHR classification in women with obesity and found that BMI value was significantly higher in the OHW compared to the NCG, but the free fat mass did not show a significant difference between all groups. In previous study of Jahanlou & Kouzekanani (2017) reporting the correlation between BMI and WHR in obese people, although WHR could influence BMI value, there was no interaction effect with FFM. These previous studies support our findings suggesting that WHR is a more important indicator than BMI for predicting obesity. However, we think that relationship between FFM and WHR needs to be systematically studied with more participants.
Obesity contributes directly not only to the pathogenesis of cardiovascular disease risk factors such as visceral adipose tissue, dyslipidaemia, diabetes and hypertension (Van Gaal et al., 2006) but also changes in metabolic syndrome risk factors including TC, TG, HDL-C, LDL-C and FG (Quijada et al., 2008). It has been well known that obese people with high WHR and WC values can be easily exposed to cardiovascular disease or metabolic syndrome (Gill et al., 2020). But, unlike previous studies, there was no statistically significant difference in cardiovascular disease risk factors in the present study. Considering these findings, the present study is inconsistent with previous study emphasized that obese people with high WHR value could be more likely to develop cardiovascular disease rather than obese people without abdominal adiposity (Hu et al., 2004). These contradictory findings in the present study are thought to be due to insufficient participants.
In addition, we confirmed that diastolic blood pressure was significantly upregulated in the OLW and OHW compared to the NCG. But this change in blood pressure is difficult to interpret because it is a difference within the normal range as well as we believe that this is because the subjects in the present study were healthy young women without any metabolic diseases.
Regular exercise is the most effective therapeutic method for preventing obesity and cardiovascular disease (Tian & Meng, 2019), and building up to vigorous level of physical fitness through exercise can bring about decrease of the WHR risk level in obese people (Söderlund et al., 2009). Taken together, these previous studies on exercise and obesity suggest that there may be a high correlation between physical fitness level and WHR in obese people. We investigated basic physical fitness and isokinetic knee and trunk muscle functions according WHR classification in obese women. As a result, we found that the lower extremity muscle function was significantly decreased in the OHW and OLW compared to the NCG. But maximal strength, flexibility, cardiorespiratory endurance, and trunk muscle function were no significant difference among groups. Lockie et al. (2020) reported that obese people with high-risk WHR cut-off value (0.85 or higher for women, 0.9 or higher for men) performed less muscular endurance, agility, and power capacity compared with obese people with low-risk WHR cut-off value (Masitoh et al., 2022). Also, Chen et al. (2020) reported that WHR might be better than BMI in measuring obesity-related decreased physical fitness. These results are consistent with the present results that high WHR values might decrease physical fitness in obese people.
Given these results reported in this study, if obese young women strive to maintain low WHR values, they may have improved health benefits over obese women with high WHR values through preventing decreases in physical fitness and lower extremity muscle functions.
| Variables | NCGa | OLWb | OHWc | F | p | Post-hoc |
|---|---|---|---|---|---|---|
| Age (year) | 19.67±0.42 | 21.70±0.26 | 20.77±0.60 | 3.390 | .039 | |
| Height (cm) | 164.37±2.02 | 161.24±0.73 | 160.99±1.77 | .818 | .445 | |
| Weight (kg) | 58.18±2.47 | 65.32±1.56 | 72.33±3.88 | 2.965 | .057 | a<c |
| Waist circumference (cm) | 74.55±2.53 | 80.28±0.96 | 89.80±1.80 | 11.552 | .001 | a<c |
| Hip circumference (cm) | 97.68±1.52 | 100.49±0.92 | 102.30±2.19 | .842 | .435 | |
| Body fat mass (kg) | 16.97±0.60 | 24.04±0.96 | 28.84±2.54 | 5.015 | .009 | a<c |
| Percent body fat (%) | 29.23±0.25 | 36.23±0.59 | 39.58±1.63 | 9.564 | .001 | a<b,c |
| Variables | NCGa | OLWb | OHWc | F | p | Post-hoc |
|---|---|---|---|---|---|---|
| Systolic blood pressure (mmHg) | 108.33±2.70 | 114.11±1.19 | 116.00±1.55 | 1.554 | .218 | |
| Diastolic blood pressure (mmHg) | 64.33±2.03 | 71.91±0.84 | 76.00±1.71 | 6.528 | .002 | a<b,c |
| Total cholesterol (mg/dL) | 176.00±14.33 | 198.97±4.62 | 194.15±9.62 | 1.119 | .332 | |
| Triglycerides (mg/dL) | 104.00±14.45 | 160.80±9.73 | 158.69±17.87 | 1.625 | .203 | |
| High-density cholesterol (mg/dL) | 67.67±5.04 | 62.58±1.96 | 60.54±10.14 | .259 | .772 | |
| Low-density cholesterol (mg/dL) | 88.17±12.81 | 103.01±3.77 | 109.54±8.42 | 1.025 | .364 | |
| Fasting blood glucose (mg/dL) | 91.67±2.69 | 94.72±1.14 | 96.69±2.44 | .665 | .517 |
| Variables | NCGa | OLWb | OHWc | F | p | Post-hoc |
|---|---|---|---|---|---|---|
| grip strength (kg) | 26.57±2.00 | 26.41±0.96 | 29.06±3.87 | .497 | .610 | |
| Back strength (kg) | 58.42±7.03 | 60.25±2.53 | 54.19±7.79 | .436 | .648 | |
| Trunk flexion in sitting position test (cm) | 14.25±3.21 | 14.92±1.44 | 12.34±2.05 | .313 | .732 | |
| Trunk back extension test (cm) | 46.80±2.13 | 44.71±1.09 | 43.07±2.22 | .422 | .657 | |
| Sit-up (reps) | 21.67±2.03 | 18.57±1.40 | 19.23±3.01 | .231 | .794 | |
| Physical efficiency index (score) | 48.68±0.85 | 48.86±0.58 | 47.22±1.11 | .745 | .478 | |
| Sergeant jump (cm) | 30.83±0.54 | 24.94±0.49 | 25.38±0.70 | 7.282 | .001 | b,c<a |
| sit-to-stand (reps) | 34.67±5.57 | 34.00±0.87 | 33.00±1.40 | .138 | .871 |
| Variables | NCGa | OLWb | OHWc | F | p | Post-hoc | ||
|---|---|---|---|---|---|---|---|---|
| Knee extension/Flexion peak torque (60°/sec) | Right | Extensors (Nm) | 112.83±11.38 | 101.80±3.52 | 110.00±7.18 | .804 | .451 | |
| Extensors (%BW) | 166.17±31.53 | 147.80±5.34 | 154.08±8.23 | .540 | .585 | |||
| Flexors (Nm) | 66.00±8.76 | 49.17±1.96 | 50.23±3.83 | 3.087 | .051 | c<a | ||
| Flexors (%BW) | 96.67±19.46 | 72.63±3.01 | 71.15±4.96 | 2.559 | .084 | |||
| H:Q Ratio | 58.67±4.87 | 48.42±1.20 | 45.92±1.77 | 3.983 | .022 | b,c<a | ||
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| Left | Extensors (Nm) | 110.67±9.47 | 101.20±3.60 | 104.92±7.41 | .369 | .693 | ||
| Extensors (%BW) | 158.67±29.77 | 150.41±5.09 | 146.46±7.32 | .175 | .839 | |||
| Flexors (Nm) | 63.17±7.46 | 48.13±1.85 | 49.38±3.19 | 2.911 | .060 | |||
| Flexors (%BW) | 91.17±18.12 | 71.48±2.80 | 70.31±4.17 | 2.006 | .141 | |||
| H:Q Ratio | 57.17±3.62 | 48.30±1.41 | 47.92±2.10 | 1.969 | .146 | |||
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| Deficit | Extensors | 6.33±2.09 | 9.95±1.07 | 14.62±3.10 | 2.191 | .118 | ||
| Flexors | 11.83±3.09 | 11.42±1.33 | 8.92±2.39 | .344 | .710 | |||
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| Knee extension/Flexion average power per repetition (240°/sec) | Right | Extensors (Nm) | 110.67±11.24 | 101.09±3.71 | 94.92±8.97 | .579 | .563 | |
| Extensors (%BW) | 161.83±30.76 | 163.25±14.28 | 136.23±11.69 | .364 | .696 | |||
| Flexors (Nm) | 75.50±9.24 | 56.05±2.32 | 55.54±5.39 | 2.958 | .058 | c<a | ||
| Flexors (%BW) | 108.00±21.41 | 82.52±3.64 | 77.38±6.81 | 2.231 | .114 | |||
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| Left | Extensors (Nm) | 108.17±12.43 | 99.41±3.70 | 109.77±7.01 | .848 | .432 | ||
| Extensors (%BW) | 152.33±29.87 | 146.97±5.28 | 153.38±6.94 | .149 | .862 | |||
| Flexors (Nm) | 77.50±5.26 | 57.38±2.15 | 61.23±3.75 | 4.185 | .019 | b<a | ||
| Flexors (%BW) | 110.17±20.40 | 85.30±3.44 | 84.00±5.83 | 2.147 | .124 | |||
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| Trunk flexion/Extension peak torque (30°/sec) | Extensors (Nm) | 97.00±11.05 | 105.47±4.38 | 123.31±13.14 | 1.547 | .219 | ||
| Extensors (%BW) | 146.17±27.60 | 155.89±6.02 | 171.38±15.13 | .672 | .513 | |||
| Flexors (Nm) | 194.00±23.88 | 175.66±6.61 | 179.85±15.81 | .331 | .719 | |||
| Flexors (%BW) | 281.67±56.51 | 255.97±9.57 | 251.54±18.76 | .316 | .730 | |||
| H:Q Ratio | 51.50±6.07 | 63.56±3.10 | 73.62±10.51 | 1.505 | .228 | |||
