KINANTHROPOMETRY Somatotype and its association with body mass index, body fat, and muscle mass among adult male elite weightlifters of Merida, Mexico

Aim: To evaluate somatotype and its association with body mass index (BMI), body fat (%), and muscle mass (%) among adult male elite weightlifters in Merida, Mexico. Methods: Eight elite male weightlifters, age ranged from 20-29 year were studied at Yucatan State Sports Institute of Mexico. Height, weight, skinfolds (biceps, triceps, subscapular, iliac crest, supraspinale, thigh, and calf), girths (mid-upper arm relaxed and flexed, mid-thigh, and calf) and breadths (humerus, femur) were recorded. BMI, body fat (%), muscle mass (%), and somatotype were estimated. Phantom Z-score values (Zp scores) were calculated to estimate similarity of body size and proportionality. Results: Average age of the participants was 25.80±1.6 years. Average endomorphic mesomorph somatotype (3.8-7.1-0.5) was observed in the present study. Endomorphy showed significant (p<0.05) correlation with BMI (r= 0.80), percent body fat (r= 0.98), and percent muscle mass (r= -0.91). Mesomorphy was significantly correlated with percent muscle mass (r= 0.65, p<0.05). BMI had correlation with percent body fat (r= 0.70, p<0.05) and percent muscle mass (r= -0.55, p>0.05). Simultaneous increase of body fat and muscle mass with the rise of body weight of the weightlifters were evident. Body weight, breadths and circumferences had positive Zp scores whereas skinfolds had negative Zp scores. Conclusions: Somatotype of elite weightlifters showed higher relative muscularity and lower body fatness. Somatotype was observed to be a reliable indicator to distinguish between body fatness and leanness.

Weightlifting is a popular sport in Mexico, and it demands muscular strength to create force to lift the weight against gravity. A blend of muscle mass, relatively lower body fat, relative short limb lengths, more muscle mass in the arm and endomorphic mesomorph somatotype may help the weightlifters for better sport performance (Fry et al. 2006, Vidal Pérez et al. 2021). Short stature, relatively short subischial leg length, and high body fat characterize the physique of the Maya ethnic group of Yucatan Peninsula in Mexico and Guatemala Varela-Silva 2010, 2012). Paucity of reports on morphological characteristics of weightlifters from Yucatan raised our interest to document the information of elite weightlifters from the state. The aim of the present study was to evaluate somatotype and its association with BMI, body fat (%), and muscle mass (%) among adult male elite weightlifters in Merida, Mexico.

Materials and Methods
Participants A cross-sectional study was carried out among 30 adult male weightlifters aged 20 to 29 years in the month of February-March 2019 at Yucatan State Sports Institute (IDEY in Spanish acronym) (Centro Deportivo Kukulcán) in Merida, Mexico. Among them, elite weightlifters (n = 8) were selected for the present study who had participated in the championships at national and international levels. The convenience sample was not representative. The research project was evaluated by the appropriate institutional committee (see Acknowledgements).

Anthropometric parameters
Recording of anthropometric measurements followed the guideline of International Society for the Advancement of Kinanthropometry (ISAK) (Esparza-Ros et al. 2019). Height, weight, girths (relaxed and flexed mid-upper arm, thigh, and calf), skinfolds (biceps, triceps, subscapular, iliac crest, supraspinale, mid-thigh, and calf), and breadths (humerus, femur) of the weightlifters were measured by an ISAK level 3 criterion anthropometrist (SDB). Data were recorded in the morning, before any physical exercises and heavy breakfast.
Body weight was measured to the nearest 0.05 kg using an electronic weighing scale (Seca ®, model 881, Hamburg, Germany), and height to the nearest 0.1 cm using a standard anthropometer (Seca ®, Germany). Percutaneous measurements were recorded on the right side of the body; breadths were recorded using a standard sliding caliper (CESCORF ®, Brazil); circumferences using standard tape (Lufkin)-both to the nearest 0.1 cm, and skinfold thickness nearest 0.1 mm using a Harpenden skinfold caliper. Intra-observer technical error of measurement was within acceptable limits; anthropometric measurement had intraclass correlation coefficient >0.85 (Altman 1999).
Body mass index (BMI) was estimated using the formula [BMI= weight (kg)/height 2 (m)] (WHO 1995). Height-to-weight ratio was calculated. Body fat (%) was estimated using standard equation = (4.95/density -4.50) x 100 (Siri 1956). Density was calculated using standard formulas by age of the participants (Durnin and Womersley 1974). A pre-validated formula was used to estimate skeletal muscle mass (kg and %) (Lee et al. 2000) that showed agreement with the results obtained using dual-energy X-ray absorptiometry (González-Mendoza et al. 2019). Somatotype rating was done using standard formulas (Carter and Heath 1990).
Distribution of anthropometric data in different body weight categories as per guideline of the International Weightlifting Federation for Olympic Games (IWF 2015) was done to observe differences in morphological characteristics of the weightlifters in the groups. Phantom Z-score values (Zp scores) were used to estimate relative body size and proportionality of the participant weightlifters Marfell-Jones 1991, Ross andWilson 1974).
Microsoft Excel ® and SPSS software (Statistical Package for Social Sciences) (Version 15.00, Chicago IL, USA) were used for data analysis, somatotype rating and calculation of Phantom Z-scores. Anthropometric data were found to be within acceptable limits of normal distributions (Shapiro-Wilk test, p<0.05). Descriptive statistics of mean and standard deviation values were calculated. One-way Analysis of Variance was done to find significant differences between the mean values of independent variables; correlation coefficients were used to find association between variables. Statistical significance was set a priori at p<0.05.

Results
Mean value of age of young male weightlifters was 25.80 years, ranging between 20 and 29 years. Body weight of the weightlifters also had a wider range (74 to 101 kg) with a mean value 88.46 kg. Similarly, stature showed a mean value of 170.3 cm, ranged between 158 and 179 cm. Mean value of BMI was 30.59 kg/m 2 where majority of the weightlifters were overweight and obese (only one individual had normal BMI of 24.02 kg/m 2 ). Body fat (%) of the athletes was relatively low (16.86%) with higher muscle mass (39.62 kg, 44.84%) ( Table 1). Weightlifters in the present study had endomorphic mesomorph somatotype (3.8-7.1-0.5) in average with a wide range of mesomorphy component (5.2 to 8.5) ( Table 2). When plotted on the somatochart, the weightlifters were observed in the mesomorph endomorph and endomorphic mesomorph zones (Figure 1).  Distribution of anthropometric characteristics and somatotype of the weightlifters according to the body weight categories was presented in Table 3. Consistent increase of mean values of BMI, body fat (%), muscle mass (%), endomorphy, and mesomorphy components with the higher weight categories were observed. However, differences of mean values were not significant (p>0.05). BMI showed significant positive correlation (p<0.05) with body fat (%) (r = 0.70), endomorphy component (r = 0.80) and negative correlation with muscle mass (r = -0.55, p = 0.15) and ectomorphy component (r = -0.92, p<0.0001). Body fat (%) also showed significant (p<0.0001) negative correlation with muscle mass (%) (r = -0.90) and positive correlation with endomorphy component (r = 0.98). Muscle mass showed significant correlation with the three components: endomorphy (r = -0.91), mesomorphy (r = 0.65), and ectomorphy (r = -0.74) ( Table 4).

Discussion
The purpose of the study was to estimate body type (somatotype) of adult male elite weightlifters and evaluate its interrelationships with BMI, body fat (%), and muscle mass (%). The weightlifters had endomorphic mesomorph somatotype, in average; relative fatness (endomorphy) showed significant positive correlation with BMI and body fat (%). The weightlifters had notable musculoskeletal development relative to height (mesomorphy). BMI had significant positive correlation with body fat (%) and negative correlation with percentage muscle mass and relative linearity (ectomorphy). Body fat (%) showed negative interrelationship with muscle mass (%). Therefore, it was evident that BMI was not a reliable indicator to distinguish between body fat and lean body mass (positive correlation with percentage body fat, endomorphy, and mesomorphy components). On the other hand, somatotype could clearly distinguish between relative fatness, musculoskeletal development relative to height, and relative linearity and had corresponding interrelationships with percentage body fat and muscle mass.
Body proportion and composition are important aspects for the development of athletic skill and performance. Therefore, anthropometric evaluation of the parameters can document physical and physiological aspects of athletes representing a country and can be used to compare with the profiles of athletes from other DOI: 10.34256/ijk2118 countries, along with their levels of competence. Average body weight of the weightlifters in the present study was 88.46 kg, which value was higher than the average body weight (75.2 kg) of elite Spanish male weightlifters (Canda 2012). Yucatec weightlifters were relatively short (average 170.3 cm, ranged between 158 and 179 cm) in comparison with that of Spanish weightlifters (179.5 cm). However, variation of body size and proportions across the populations in the world was reported (Bogin and Varela-Silva 2010). Short height was reported to be advantageous for the weightlifters (Canda 2012) but another studiys showed that taller weightlifters with higher body weight also had remarkable advantages (Huebner and Perperoglou 2020). The weightlifters with short height, short arms, low body fat, and high muscularity had higher relative strength and power than others (Carter 1982, Ford et al. 1985, Fry et al. 2006, Mayhew et al. 1993. Body fat (%) of the participant weightlifters in the present study (16.86%) was higher than the recommended values for men (5-12%) (Wilmore and Costill 2007) and also that of Spanish weightlifters (10%) (Vidal Pérez et al. 2021). However, relative fatness was lower than relative muscularity of the weightlifters in the present study. Muscle mass (%) estimated among the participant weightlifters (44.84%) was lower than that value reported earlier (51.6%) (Vidal Pérez et al. 2021) though the guidelines for evaluation were different in these studies.
It was reported that adult male weightlifters in weight categories had different body types (Stone et al. 2006). Somatotype of weightlifters ≤85 kg body weight category was ectomorph or mesomorph with 5-10% body fat (Orvanová 1990), and heavy-weight weightlifters were endomorphic mesomorphs (Stone et al. 2006). Sample size of the present study was relatively small (n = 8). However, results obtained in the present study at different body weight categories (<81 kg, <89 kg, < 96 kg, and < 102 kg) were concordant with those reported earlier (Fry et al. 2006, Orvanová 1990Stone et al. 2006. Yucatec weightlifters of higher body weight categories had higher BMI, body fat (%), muscle mass, endomorphy and mesomorphy components in comparison with peers in the lower body weight categories.
The young adult male elite weightlifters in the present study had endomorphic mesomorph somatotype (3.8-7.1-0.5) in average that exhibited a blend of high muscularity with relatively low body fatness. Somatotype of high-performance weightlifters from Colombia was endomorphic mesomorph (3.1-4.2-1.7) (Barajas Ramon and Santana Lobo 2010), which was very similar to the results obtained in the present study. However, mesomorph component of the weightlifters from Merida was higher than that of Colombian weightlifters. The Colombian weightlifters had lower BMI (25 kg/m 2 ) and body fat (10%) in comparison with the characteristics of weightlifters of Merida, Mexico (30.59 kg/m 2 , 16.86%, respectively). Quelal López (2013) reported lower body fat (12%), and endomorphic mesomorph somatotype (2.9-7.8-1.0) of the weightlifters (69 to 80 kg body weight category) from Ecuador with age range of 15-20 year. Somatotype of weightlifters from Latin American countries were similar, independent of other morphological characteristics. Adult weightlifters (above 20 years of age) from Spain also had similar somatotype (2.2-7.2-0.9), showing relatively higher muscularity (Lopez and Aragones 1989). Kutseryb and colleagues (2017) reported endomorphic mesomorph somatotype (2.9-5.7-2.3) in average for Ukrainian weightlifters with a notable ectomorphy component.

Limitations
Limitations of the study include first the type of sample (convenience) that was relatively smaller and drawn from a single sports complex (IDEY). Bigger sample size and data from other regions of Mexico could have comparative estimates of physical characteristics of the weightlifters. In addition, comparative statement of the characteristics of body proportion and composition of the Yucatec weightlifters with that of weightlifters of Olympic Games could enrich the study. Data on barbell velocity in squat Snatch and Clean & Jerk and their association with morphological characteristics of the weightlifters could show more precise results that will be considered in future studies. Non-availability of data of female weightlifting athletes was another limitation.

Conclusion
The present study contributes important information of physical characteristics of elite male weightlifters from Merida, Mexico. In agreement with the previous studies among weightlifters reported from Latin American and other countries, the present study showed endomorphic mesomorph somatotype with relatively high muscularity, and low body fat of the weightlifters despite smaller sample size. Simultaneous increase of body fat and muscle mass with the rise of body weight of the weightlifters was evident. The information will offer an understanding of morphological characteristics of Yucatec weightlifters that will help athletes, coaches, trainers, nutritionists, health, and other sport professionals to improve sports performance.