Hydration is an important consideration within athlete preparation, training and recovery. But for performance practitioners, the challenge is rarely knowing that hydration matters. The bigger question is:
How do you monitor hydration consistently across your athletes, and how do you turn that information into something useful?
For S&C coaches, sports scientists and sports nutritionists, hydration monitoring can provide valuable insight into an athlete's fluid status and help inform individualised hydration strategies.
There isn't one method that suits every environment, however.
Some programmes may benefit from a simple handheld measurement during scheduled testing. Others may want a faster digital method that can be used across a squad. And for teams looking to make hydration monitoring part of an athlete's normal routine, automated testing can provide a different approach altogether.
Perform Better offers three options for measuring urine specific gravity (USG), allowing practitioners to choose the approach that best fits their environment:
Why monitor hydration?
Fluid losses during exercise occur primarily through sweating, with the amount varying significantly between athletes and according to the demands of the session.
Exercise duration and intensity, environmental conditions, clothing, body size, sweat rate and individual physiology can all influence fluid losses. For this reason, hydration strategies should be individualised rather than based on a single fluid target for an entire squad.
Significant fluid losses can affect cardiovascular and thermoregulatory function and may negatively affect exercise performance, particularly during prolonged or high-intensity exercise and in hot environments.
At the same time, effective hydration isn't simply about encouraging athletes to drink as much as possible. Excessive fluid intake during prolonged exercise can contribute to exercise-associated hyponatremia.
For performance teams, the objective is therefore to understand the athlete, monitor relevant markers and use the information to develop an appropriate strategy.
What is urine specific gravity?
Urine specific gravity (USG) is a measure of the concentration of particles dissolved in urine.
It is commonly used as one indicator of hydration status, with more concentrated urine generally producing a higher USG reading.
USG can be assessed using refractometry, providing practitioners with an objective measurement rather than relying solely on subjective indicators such as urine colour or thirst.
It is important to remember that no single hydration measure provides the complete picture.
USG can be considered alongside other information such as:
- Pre- and post-training body mass
- Sweat rate
- Sweat sodium concentration
- Fluid intake
- Exercise duration and intensity
- Environmental conditions
- Athlete-reported thirst
- Training and competition schedule
The most useful approach will depend on the athlete, the sport and the purpose of the assessment.
Three approaches to hydration monitoring:
1. Portable Refractometer — simple, portable USG assessment
For practitioners who want a compact and straightforward method of measuring urine specific gravity, a portable refractometer can provide an effective solution.
The Portable Refractometer requires only a small urine sample and provides an immediate specific-gravity reading. Its compact design makes it suitable for use within a performance facility, testing environment or when equipment needs to be transported between locations.
Why might a practitioner choose a portable refractometer?
It can be particularly useful when hydration testing is incorporated into:
- Scheduled athlete screening
- Research or data-collection protocols
- Individual athlete assessments
- Pre-training or pre-competition testing
- Sweat-rate and fluid-balance assessments
- Smaller squads where testing is conducted manually
For a sports scientist, the main benefit is having a portable method of obtaining an objective USG measurement without needing a larger laboratory setup.
For a sports nutritionist, it can form part of a broader assessment of an athlete's hydration and fluid-intake strategy.
For an S&C coach, it provides a practical way of incorporating hydration status into wider athlete monitoring where appropriate.
Best suited to: practitioners who want a straightforward, portable USG measurement and are comfortable with a manual sample-based process.
Explore the Portable Refractometer
2. Pen Portable Hydration Analyser — faster digital testing
The Pen Portable Hydration Analyser takes the same fundamental approach — measuring urine specific gravity using refractive index — but is designed to simplify the sampling process.
The device can be dipped directly into the urine sample, with the result displayed in approximately two seconds. This removes the need for pipetting and can make repeated testing more efficient.
Where could the Pen fit into a performance programme?
A digital pen refractometer may be useful for:
- Squad hydration screening
- Pre-training testing
- Pre-competition assessments
- Research and applied sports-science projects
- Monitoring hydration alongside sweat-rate testing
- Performance environments where testing speed is important
The Pen has also been used in research involving elite professional footballers, including examining fluid balance, sweat sodium losses and carbohydrate intake across different training intensities and environmental conditions.
That research highlights an important point for practitioners: hydration and fuelling strategies need to reflect the individual athlete and the exercise occasion.
The Pen can therefore sit within a broader assessment process rather than being viewed as a standalone hydration solution.
Best suited to: practitioners who want objective USG measurements but need a quicker, more streamlined manual testing process.
Explore the Pen Portable Hydration Analyser
3. InFlow — automated hydration monitoring within the athlete's routine
For larger squads or environments where frequent hydration monitoring is difficult to maintain manually, InFlow takes a different approach.
Rather than requiring athletes to provide a sample for a practitioner to analyse, InFlow is fitted directly to a urinal and uses optical sensing technology to assess urine in real time. The device provides immediate visual feedback through a green, yellow or red result.
Current InFlow thresholds are based on urine specific gravity:
- Green — below 1.012: hydrated
- Yellow — 1.012–1.025: mild dehydration
- Red — above 1.025: significant dehydration
The purpose isn't to replace practitioner judgement. Instead, it is designed to make objective hydration feedback available as part of the athlete's normal routine.
Why is that useful in a team environment?
Manual hydration testing can be difficult to maintain across a large squad.
Athletes need to provide samples, staff need to conduct measurements and results need to be recorded and communicated.
InFlow removes much of that process.
The athlete simply uses the urinal as normal and receives an immediate result.
For performance departments, this creates the potential for more frequent monitoring without requiring additional testing appointments or staff-led sample collection.
For sports scientists
InFlow can provide a practical way of introducing more frequent hydration checks into the athlete environment. Rather than relying solely on occasional testing points, practitioners can observe patterns and use those observations alongside other performance data.
For sports nutritionists
Immediate feedback can support conversations around individual fluid and electrolyte strategies. Rather than relying entirely on an athlete's perception of their hydration, practitioners have another objective measure that can be considered alongside dietary intake, sweat losses and training demands.
For S&C coaches
Hydration can be incorporated into the wider performance environment without creating another formal testing process for athletes to complete. The immediate feedback can also help athletes take greater ownership of their own hydration habits.
Best suited to: teams and performance environments looking for frequent, automated hydration monitoring with minimal additional staff involvement.
Which hydration monitoring approach is right for your programme?
The right choice depends less on which technology is "best" and more on what you are trying to measure and how you need to use the information.
The important consideration is the role hydration testing needs to play within your programme.
If you're conducting scheduled testing or research, a portable refractometer may be all you need.
If you're already conducting manual testing but want to make the process quicker and easier, the Pen provides a digital alternative.
If your objective is to make hydration monitoring a continuous part of the team environment, InFlow provides a fundamentally different approach.
Portable Refractometer: for straightforward, portable USG assessment.
Pen Portable Hydration Analyser: for fast, digital USG testing with minimal sample handling.
InFlow: for automated hydration monitoring integrated into the athlete's everyday routine.
Talk to the Perform Better team about your current testing process, squad size and performance environment. We can help you explore which hydration-monitoring approach best fits your programme.
