Table 2.

Example Hydration Testing Protocols for Athletes

	Individual A (Competitive boxer who has just made weight)	Individual B (Cricket player playing in a 5-day test match)	Individual C (Marathon runner preparing for a major competition with two prior qualifying events)
Logistics	• The weigh-ins are conducted at a stadium by the regulating commission away from laboratory equipment 24 h before the event. • There was no availability for pre-weight loss measures • Athlete needs to begin rehydrating as soon as possible • Coach and athlete preference is to avoid blood draws so close to competition	• The competition situation is located away from a laboratory • Measures can be taken before and after the day’s play as well as between sessions of play • The player will be ingesting fluids throughout the day • Antecubital blood draws are not permitted	• Historical environmental evidence suggests that the athlete will be competing in hot and humid environments, as such the decision taken by the coach and support team is to implement a heat acclimation strategy • Events are separated by approximately 14 weeks, beginning 7 weeks before the event, a 6 week heat acclimation protocol inclusive of adaptation monitoring will be instigated for a 7 day taper into the event • In addition, support staff wish to know if the competition hydration strategy implemented at each event is suitable • At each event, testing will take place 2 h prior, as soon as practically possible after finishing and 1 h this post race collection
Suggested tests	• Urine specific gravity • Body mass recovery between the weigh-in and the competition • Tear osmolality	• Urine specific gravity • Sensation of thirst • Body mass change	• Urine specific gravity • Serum osmolality • Haematocrit • Tear osmolality • Sensation of thirst • Body mass
Reasoning	The above protocol involves testing two different body fluids which can be easily assessed at an external location. Additionally, there is a gross marker of hydration (body mass change), which can help provide a more complete hydration picture. Importantly if too much body mass (> 15%) was regained by the competition, then the bout could be cancelled, or the athlete could be required to move up a weight class for their next competition. Sensation of thirst was not selected as the athlete may not answer honestly in an effort to mask dehydration.	The above protocol requires only involves a single (convenient) measure of a bodily fluid but includes two gross markers of hydration status. When beginning monitoring prior to the first session of play, the protocol relies on USG and sensation of thirst, whereas changes in body mass can be used throughout the day to prescribe fluid intake. The waking body mass from the first day can then also be used to interpret subsequent morning measurements, and between sessions of play. Provided, the fluid intake during the session is measured, this does allow for a highly accurate understanding of hydration status change.	The above protocol involves the assessment of three different bodily fluids and two gross markers of hydration status. This combination will provide a more complete assessment of whole body hydration and consistency of assessment technique from the acclimation period through to event. The pre-event testing protocol can be completed within 30 min enabling recommendations to be quickly given and responses implemented prior to competition if necessary. The post-event testing will be able to confirm if the hydration strategies used during the event were sufficient and ideally not a limiting factor to performance.
Considerations	While the suggested protocol involves the assessment of multiple bodily fluids, the reliability of spot urine assessments is questionable and the validity/reliability behind tear osmolality is still unclear. However, if the fluid markers indicate hypohydration and a large amount of body mass is regained between weigh-in and competition, then the athlete’s support staff can be confident that they were significantly hypohydrated at the weigh-in and make the decision whether to cancel the bout or strongly recommend that the athlete change weight classes for future bouts.	Application of this method is best in a well-controlled situation, with the most important factor being controlling/measuring all food/fluid that athletes take in across the multiple days of competition. In situations where some measures suggest hypohydration and others do not, it is best to encourage the athlete to ingest fluids.	By implementing acclimation strategies prior to each event, training load, individual physiological adaptation, and familiarity with testing processes can continue to be refined. Continual education of the athlete can be achieved during each acclimation period and qualification event to the signs and extent of any indication of hypohydration, leading to a more self-aware athlete for the need to ingest additional fluids. Support staff should seek to take note of the relationship between the less invasive markers and those derived from invasive measures to better contextualise individual response. Understanding this individual response for each marker and their relationship can allow for the possibility at the major event, to remove the invasive blood markers and rely on the non-invasive tests in an effort to reduce any potential influence and anxiety the athlete may hold for their performance.