Not a clinical trial study

Dehydration can result from exposure to harsh environments including hot and dry desert climates. Soldiers and non-military workers are frequently required to work in hot, dry conditions, and dehydration can be productivity limiting and life threatening if unrecognized.

The research can use low power laser technology to take measurements of muscle tissue water content in volunteers before and after marathon training runs to detect dehydration. Two slightly different devices can be used to detect dehydration. 1). diffuse optical spectroscopy and 2). spatial frequency domain imaging-modulated imaging The researchers can determined by use other methods to assess the level of dehydration status in runners. These methods will include taking weight and temperature before and after run, skin-fold measurements pre and post run, and obtaining saliva samples from before and after run. The researchers can determine the study use non-invasive, laser light technology measure tissue water concentrations, as an indicator of dehydration.

Inclusion Criteria:

• male female ages of 18 and 60
• training for a marathon

Exclusion Criteria:

1. Poorly controlled diabetes mellitus
2. Diabetes insipidus (excessive urination of water) as diagnosed by your physician
3. disorder of the intestine
4. Irritable bowel syndrome with excessive diarrhea, as diagnosed by a physician
5. Congestive heart failure and subsequent use of a diuretic "water pill" to remove excess water from the body
6. Have poor kidney function
7. Have been diagnosed with hyperthyroidism/hypothyroidism by your physician

Study population are the volunteers who are training for a marathon individually or under the guidance of the Leukemia Society Team in Training, the American Heart Association, or similar groups. These organizations run programs that include providing group-training situations for individuals interested in preparing for a marathon while participating in fund raising efforts.