Abstract
Surface electromyography (sEMG) is an important tool to estimate muscular activity at work. There is, however, a great inter-individual variation, even in carefully standardized work tasks. The sEMG signal is attenuated in the subcutaneous tissues, differently for each subject, which requires normalization. This is commonly made in relation to a reference contraction, which by itself, however, introduces a variance. A normalization method that is independent of individual motivation, motor control and pain inhibition would be desirable. The aim of the study was to explore the influence of the subcutaneous tissue thickness on sEMG amplitude. Ultrasound measurements of the muscle to skin surface distance were made bilaterally over the trapezius muscle in 12 females. Skinfold caliper measurements from these sites, as well as from four other sites, were made, body mass index (BMI) was recorded, and sEMG was recorded at maximal and submaximal contractions. The muscle–electrode distance, as measured by ultrasound, explained 33% and 31% (on the dominant and non-dominant sides respectively) of the variance of the sEMG activity at a standardized submaximal contraction (average between the sides, 46%); for maximal contractions the explained variance was 21%. Trapezius skinfold measurements showed poor correlations with sEMG. Instead, the mean of skinfold measurements from other sites explained as much as 68% (submaximal contraction). The corresponding figure for BMI was 67%. In conclusion, skinfold thickness explains a major part of the inter-individual variance in sEMG amplitude, and normalization to this measure is a possibility worth further evaluation.
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Åkesson I, Hansson G-Å, Balogh I, Moritz U, Skerfving S (1997) Quantifying work load in neck, shoulders and wrists in female dentists. Int Arch Occup Environ Health 69:461–474
Balogh I, Hansson G-Å, Ohlsson K, Strömberg U, Skerfving S (1999) Interindividual variation of physical load in a work task. Scand J Work Environ Health 25:57–66
Basmajian JV, Luca CJd (1979) Muscles alive. Their functions revealed by electromyography. Williams and Wilkins, Baltimore, Md.
Booth RA, Goddard BA, Paton A (1966) Measurement of fat thickness in man: a comparison of ultrasound, Harpenden calipers and electrical conductivity. Br J Nutr 20:719–725
De Luca CJ (1979) Physiology and mathematics of myoelectric signals. IEEE Trans Biomed Eng 26:313–325
Durnin JV, Rahaman MM (1967) The assessment of the amount of fat in the human body from measurements of skinfold thickness. Br J Nutr 21:681–689
Durnin JV, Womersley J (1974) Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 32:77–97
Gwinup G, Chelvam R, Steinberg T (1971) Thickness of subcutaneous fat and activity of underlying muscles. Ann Intern Med 74:408–411
Hansson G-Å, Asterland P, Skerfving S (1997) Acquisition and analyses of whole-day electromyographic field recordings. In: Hermens HJ, Hägg G, Freriks B (eds) Proceedings of the second general SENIAM (Surface EMG for Non Invasive Assessment of Muscles) workshop. Roessing Research and Development, Stockholm, Sweden, pp 19–27
Hansson G-Å, Asterland P, Kellerman M (2003) Modular data logger system for physical workload measurements. Ergonomics 46:407–415
Heitmann BL (1990) Evaluation of body fat estimated from body mass index, skinfolds and impedance. A comparative study. Eur J Clin Nutr 44:831–837
Hemingway MA, Biedermann HJ, Inglis J (1995) Electromyographic recordings of paraspinal muscles: variations related to subcutaneous tissue thickness. Biofeedback Self Regul 20:39–49
Hermens HJ, Hägg G, Freriks B (1997) Proceedings of the second general SENIAM workshop. European applications on surface electromyography, Roessingh Research and Development, Stockholm, Sweden
Jensen C, Vasseljen O, Westgaard RH (1993) The influence of electrode position on bipolar surface electromyogram recordings of the upper trapezius muscle. Eur J Appl Physiol 67:266–273
Larsson B, Björk J, Elert J, Gerdle B (2000) Mechanical performance and electromyography during repeated maximal isokinetic shoulder forward flexions in female cleaners with and without myalgia of the trapezius muscle and in healthy controls. Eur J Appl Physiol 83:257–267
Lowery MM, Stoykov NS, Taflove A, Kuiken TA (2002) A multiple-layer finite-element model of the surface EMG signal. IEEE Trans Biomed Eng 49:446–454
Mathiassen SE, Winkel J, Hägg GM (1995) Normalization of surface EMG amplitude from the upper trapezius muscle in ergonomic studies – a review. J Electromyogr Kinesiol 5:197–226
Nordander C, Hansson G-Å, Rylander L, Asterland P, Unge Byström J, Ohlsson K, Balogh I, Skerfving S (2000) Muscular rest and gap frequency as EMG measures of physical exposure: the impact of work tasks and individual related factors. Ergonomics 43:1904–1919
Norlund A, Pålsson B, Ohlsson K, Skerfving S (2000) Economic consequences of occupational disorders in women with repetitive industrial work. Eur J Publ Health 10:127–132
Ohlsson K, Hansson G-Å, Balogh I, Strömberg U, Pålsson B, Nordander C, Rylander L, Skerfving S (1994) Disorders of the neck and upper limbs in women in the fish processing industry. Occup Environ Med 51:826–832
Orphanidou C, McCargar L, Birmingham CL, Mathieson J, Goldner E (1994) Accuracy of subcutaneous fat measurement: comparison of skinfold calipers, ultrasound, and computed tomography. J Am Diet Assoc 94:855–858
Palmerud G, Sporrong H, Herberts P, Kadefors R (1998) Consequences of trapezius relaxation on the distribution of shoulder muscle forces: an electromyographic study. J Electromyogr Kinesiol 8:185–193
Ranney D, Wells R, Moore A (1995) Upper limb musculoskeletal disorders in highly repetitive industries: precise anatomical physical findings. Ergonomics 38:1408–1423
Rempel D (1998) Estimating muscle load using surface EMG amplitude. Marconi Research Conference, University of California, Marshall
Roeleveld K, Stegeman DF, Vingerhoets HM, Van Oosterom A (1997) Motor unit potential contribution to surface electromyography. Acta Physiol Scand 160:175–183
SBU (2000) Pain in the back and neck. An evidence based compositon of knowledge [in Swedish]. SBU The Swedish Council on Technology Assessment in Health care, Stockholm
Schüldt K, Harms-Ringdahl K (1988) Activity levels during isometric test contractions of neck and shoulder muscles. Scand J Rehabil Med 20:117–127
Stegeman DF, Blok JH, Hermens HJ, Roeleveld K (2000) Surface EMG models: properties and applications. J Electromyogr Kinesiol 10:313–326
Volz PA, Ostrove SM (1984) Evaluation of a portable ultrasonoscope in assessing the body composition of college-age women. Med Sci Sports Exerc 16:97–102
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This study was supported by grants from the Swedish Medical Research Council, the Swedish Council for Work Life Research (including Change@Work), the Swedish National Institute of Working Life (Co-operative for Optimization of industrial production systems regarding Productivity and Ergonomics; COPE), the Swedish Council for Planning and Coordination of Research, AFA Insurance, the Medical Faculty of Lund University and the County Councils of Southern Sweden.
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Nordander, C., Willner, J., Hansson, GÅ. et al. Influence of the subcutaneous fat layer, as measured by ultrasound, skinfold calipers and BMI, on the EMG amplitude. Eur J Appl Physiol 89, 514–519 (2003). https://doi.org/10.1007/s00421-003-0819-1
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DOI: https://doi.org/10.1007/s00421-003-0819-1