Reliability of standard circumferences in domain-related constitutional applications.

OBJECTIVES: There may be no doubt that circumferences, measured at different sites of body segments, have a variety of applications. Studies using girths are based on assumed logic, but within a general context no literature is found as to the origin of choice of a particular circumference for a particular application. The purpose of this study is to relate each circumference (i) with the segmental tissue masses and (ii) with all whole-body tissue masses; in order to provide a complete constitutional reliability report of each girth available. METHODS: Subsequent to an anthropometric protocol, 23 (9 male aged 74.8 ± 5.7 years and 14 female aged 79.2 ± 7.3 years) well-preserved white Caucasian cadavers, of lean subjects were dissected according to the 5-component model and expressed on its tissue-system level, for example, skin, muscle, adipose tissue, viscera, and bones. RESULTS: The relations range from r = 0.80 to r = 0.99 (P < 0.01). A majority of circumferences (e.g., head, neck, upper thigh, mid-thigh, and calf) do represent what is expected. Other girths (e.g., waist, upper arm, elbow, forearm, and wrist) do not relate adequately to the assumed constituent. CONCLUSION: This study suggests the appreciation of the waist circumference. This measure is not valid for lean individuals, but might be for the obese. It is suggested likewise that a combination of chest and hip circumference may have a more general application within the public health sector. In summary, evidence confirms the reliability of a series of circumferences but creates doubts or rejects other colloquially established perimeters.

Critical appraisal and hazards of surface electromyography data acquisition in sport and exercise.

The aim of this critical appraisal and hazards of surface electromyography (SEMG) is to enhance the data acquisition quality in voluntary but complex movements, sport and exercise in particular. The methodological and technical registration strategies deal with telemetry and online data acquisition, the placement of the detection electrodes and the choice of the most adequate normalization mode.Findings compared with the literature suggest detection quality differences between registration methods and between water and air data acquisition allowing for output differences up to 30% between registration methods and up to 25% decrease in water, considering identical measures in air and in water. Various hazards deal with erroneous choices of muscles or electrode placement and the continuous confusion created by static normalization for dynamic motion. Peak dynamic intensities ranged from 111% (in archery) to 283% (in giant slalom) of a static 100% reference. In addition, the linear relationship between integrated EMG (IEMG) as a reference for muscle intensity and muscle force is not likely to exist in dynamic conditions since it is muscle - joint angle - and fatigue dependent. Contrary to expectations, the literature shows 30% of non linear relations in isometric conditions also.SEMG in sport and exercise is highly variable and different from clinical (e.g. neurological) EMG. Choices of electrodes, registration methods, muscles, joint angles and normalization techniques may lead to confusing and erroneous or incomparable results.