Hydration status measurement by radio frequency absorptiometry in young athletes—a new method and preliminary results

Abstract

A new method for non-invasive measurement of the human state of hydration is presented. This method is based on frequency-dependent absorptiometry of radio-waves passing through tissues. A device utilizing this method was constructed and applied to 12 young (24 +/- 1) male volunteers, who were dehydrated for 1-2.5% of their weight by performance of a physical effort (two 30 min bouts of treadmill walking/running at 2, 3, 4, 5, 6 and 7 mph, 5 min at each speed, separated by 10 min rest), under moderate heat stress (40 degrees C, 40% RH). Hypohydration level was determined by body weight measurements taken before each session, after 30 min and at the end of each session. Concomitantly, measurements of radio frequency (RF) absorption were taken. Each volunteer underwent the heat stress exercise twice: one in which no drinking was permitted, and another with free drinking. A correlation (R2 = 0.734) between weight loss and a change in the radio-waves absorption pattern was observed in most of the volunteers, in both hypo and euhydration sessions. Further work to establish the reproducibility and validity of the RF methodology in larger and different populations, i.e., females, other age groups and different health conditions, is already being researched.

A Review on Opportunities To Assess Hydration in Wireless Body Area Networks

“…In 2003, Moran et al [33] demonstrated the use of electromagnetic waves for assessment of hydration on 12 male subjects in a climatic chamber. The subjects were subjected to heat stress in various degrees.…”

“…The results are affected by changes in posture, exercise, and sodium chloride balance in the body. Some researchers have argued that plasma osmolality is only valid for changes in hydration state but not for estimating TBW [33]. The volume and concentration fluctuate with daily activities and do not respond quickly to loss of body fluid after exercise or other daily activities.…”

“…As current flows, energy is absorbed in relation to the quantity of solute available [48]. The resulting attenuation from a propagating radio frequency wave has been used to measure hydration [33,49]. In a similar manner, the attenuation of an electrical signal galvanically coupled to the body has been used to assess hydration level that indicated four different fluid states in the body [45].…”

Mechanical Dilution of Beta-amyloid Peptide and Phosphorylated Tau Protein in Alzheimer's Disease: Too Simple to be True?

“…CSF production is around 500 ml per day and it is renewed about four times every 24 hours [13, 15]. As told, reduction of the CSF turnover rate has been described in aging and in AD [13-14].…”

The Interrelationship of Research in the Laboratory and the Field to Assess Hydration Status and Determine Mechanisms Involved in Water Regulation During Physical Activity

“…In addition to these basic techniques, a number of elegant systems have been developed for use in the field to determine hydration [48]. These systems include portable refractometers to determine urine specific gravity, as well as portable urine conductivity analyzers [54] and arm radio frequency analyzers [55]. These portable instruments accurately predict urine osmolality and body mass loss, respectively [48].…”