Hydration for tween (ages 12-13) doing tennis
Training-day target 2,750 ml/day. Tennis combines long match durations with high ambient temperatures - outdoor summer tennis has one of the highest fluid-loss rates of any youth sport.
Quick answer
Hydration for tween (ages 12-13) doing tennis
Start from the EFSA total-water Adequate Intake for this age band - about 2,100 mL/day for boys 9-13 (1,900 mL/day for girls) - then add fluid to cover sweat loss on a training day. With whole-body sweat rates running roughly 0.5-2.0 L/h during exercise (Baker 2017), a hot 60-90 minute tennis session adds several hundred millilitres, landing a typical training-day total near 2,750 mL. During play, drink about 150-200 mL every 15-20 minutes and keep body-mass loss under 2% (FIFA/F-MARC 2006; ACSM 2007).
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Tweens (ages 12-13) doing tennis practice face a different hydration problem than either the general age group or the general sport. Tennis combines long match durations with high ambient temperatures - outdoor summer tennis has one of the highest fluid-loss rates of any youth sport. Matches often run 60-120 minutes of active play with minimal shade. Whole-body sweat rates during exercise typically run between 0.5 and 2.0 L/hour, and the upper end is reached in hot tournament play. Sessions and matches are at full duration; travel teams and club-level intensity begin in this band. Target 2,750 ml (2.8 L) of total fluids on a training day - approximately 650 ml above the tween (ages 12-13) baseline to cover the session's fluid loss.
Targets for tweens (ages 12-13) doing tennis practice
Training-day target for tweens (ages 12-13): 2,750 ml
Baseline for the tween (ages 12-13) age band is 2,100 ml from EFSA total-water Adequate Intake (boys 9-13 y; girls 9-13 y is 1,900 ml). tennis practice adds approximately 650 ml on top, covering the fluid lost in a typical 60-90 minute session.
Source: EFSA 2010 total-water Adequate Intake + sport-specific sweat-rate research
Pre / during / post - the only framework that matters
Start the session ahead, not catching up. For this age band and sport: a pre-session dose 60-90 minutes before, scheduled sips during, and weight-based replacement after. Non-training days use the age-band baseline only - don't over-drink on rest days.
Urine colour is the cleanest daily signal
Pale straw by the mid-afternoon bathroom visit means the athlete started the session hydrated. Dark yellow or amber before training means a pre-session 500 ml top-up, not 'just start'.
Age maturity: Sessions and matches are at full duration; travel teams and club-level intensity begin in this band.
Match intake to real session length. A preschooler's 'soccer practice' is structurally different from a teen's - don't apply teen protocols to 5-year-olds, and don't apply preschool protocols to competitive tweens.
Practical tips for this age and sport
- Pre-match: about 5-7 ml/kg in the 1-4 hours before, plus a small top-up shortly before serving
- Changeover drinks: small sips at every odd-game changeover, roughly 150-200 ml every 15-20 minutes of play
- Tournament days: keep sipping on court so total body-mass loss stays under 2%, not counting pre or post
- Ice-towel on the neck between sets - drops perceived temperature and helps comfort in the heat
- Tournament weekends: per-match bottle + between-match bottle - non-negotiable
- Electrolyte (sodium-containing) drink for any single session over 60 minutes at moderate-to-high intensity
Training-day plan - printable for the sports bag
Enter the athlete's age, weight, and sport. Get a pre/during/post schedule, a bottle-size recommendation, and a 7-day tracker for training weeks. Free, no signup to download.
Build the training plan →When to watch or act
Signs of Dehydration
- Dizziness on standing after a hard set - immediate stop, 500 ml, no return without clearance
- Urine darker than light straw before training - pre-session deficit, top up 500 ml before starting
- Performance drop in the last third of the session - a recognised hydration signal once losses approach 2% body mass, not just 'being tired'
- Headache or nausea during or after training - stop, hydrate, don't push through
Sources & Citations
- 2100 mL/day (2.1 L/day) — EFSA total-water Adequate Intake for boys 9-13 years (the tween age band; water from food plus beverages). Used here as the non-training-day baseline before sport-specific fluid losses are added.[1]
- >2% body-mass loss to avoid; 5-7 mL/kg pre-event — ACSM position stand: keep water-deficit body-mass loss under 2% to avoid compromised performance; pre-exercise, drink about 5-7 mL/kg roughly 4 hours before activity to start hydrated.[2]
- 150-200 mL every 15-20 min during play — FIFA/F-MARC consensus for play: drink small amounts often during a match to limit body-mass loss to under 2%.[3]
- ~0.5 to ~2.0 L/h — Whole-body sweat rate typical range during exercise (rates above 3.0 L/h occur in only about 2% of athletes), which is why fluid loss in a hot outdoor session can be substantial.[4]
- <2% body-mass loss target; add sodium for longer/hotter sessions — NATA recommends a rehydration beverage with sufficient (not excessive) sodium and individualized sweat-rate assessment for sessions where sweat losses are high, targeting under 2% body-mass loss.[5]
- 2% or more body-mass loss — Physical performance declines at as little as 2% body-mass loss; at or above 2%, thermoregulation, cardiovascular function and aerobic exercise are impaired - the basis for a mid-session performance drop.[6]
- [1]EFSA 2010 Water DRV — EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary Reference Values for water. EFSA Journal. 2010;8(3):1459.DOI: 10.2903/j.efsa.2010.1459
- [2]Sawka 2007 (ACSM) — Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390.PMID: 17277604DOI: 10.1249/mss.0b013e31802ca597
- [3]FIFA F-MARC Consensus 2006 — FIFA F-MARC Consensus (Nutrition for Football). J Sports Sci. 2006;24(7).DOI: 10.1080/02640410500482461
- [4]Baker 2017 — Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Med. 2017;47(Suppl 1):111-128.PMID: 28332116DOI: 10.1007/s40279-017-0691-5
- [5]McDermott 2017 (NATA) — McDermott BP, Anderson SA, Armstrong LE, et al. National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active. J Athl Train. 2017;52(9):877-895.PMID: 28985128DOI: 10.4085/1062-6050-52.9.02
- [6]Popkin 2010 — Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev. 2010;68(8):439-458.PMID: 20646222DOI: 10.1111/j.1753-4887.2010.00304.x
Last reviewed: 2026-06-22. Every figure on this page is sourced to the named primary references above.
Frequently Asked Questions
How much water does a tween kid need on a tennis practice day?
About 2,750 ml (2.8 L) of total fluids across the day. Baseline for this age band is 2,100 ml (EFSA, boys 9-13), and tennis practice adds the rest to cover the session's sweat loss.
What's the pre / during / post split for this age and sport?
Pre about 5-7 ml/kg in the hours before, during roughly 150-200 ml every 15-20 minutes, post replace by weight within 30 minutes. Add a sodium-containing drink if the session runs over 60 minutes.
What about sports drinks - does tennis practice need them at this age?
For sessions or matches over 60 minutes at moderate-to-high intensity, a drink with some sodium helps. Otherwise water + a balanced post-session meal is better than a sports drink with added sugar.
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