Hydration and Fluid Intake in Basketball Players During Training: Comparison of Different Age Categories

Abstract

There are many studies on basketball players’ hydration in the literature. However, no studies have compared the hydration status of basketball players in different age categories. Therefore, this study aims to compare the hydration status and fluid intake of male basketball players of different age categories during a training session. A total of 70 athletes, actively competing in U14 (n = 30) and U21 (n = 40) teams, voluntarily participated. Urine samples were collected before and after the session to assess hydration status via urine specific gravity (USG). Fluid intake was also individually monitored during the training. Results showed a significant interaction between time and age group in terms of USG (F_(1,68) = 23.72, p < 0.001, η² = 0.083). While dehydration levels increased in U14 players during the session, U21 players showed improved hydration. The U21 group consumed significantly more fluid (1.16 ± 0.65 L) than the U14 group (0.72 ± 0.50 L; p = 0.003). No significant correlation was found between fluid intake and hydration change in either group. These findings suggest that younger athletes may require more guidance and education regarding proper hydration habits during training.

1. Introduction

Dehydration is a serious physiological condition that occurs when fluid loss exceeds fluid intake, and is triggered by factors such as strenuous physical activity, high temperature conditions, or insufficient fluid consumption [1]. This condition can significantly reduce aerobic exercise performance, especially in hot weather conditions, and can negatively affect the body’s thermoregulatory mechanisms by disrupting fluid–electrolyte balance [2,3]. Although sweating is the body’s primary cooling mechanism, it can increase the risk of dehydration, threatening athletes’ performance and health when combined with inadequate fluid intake.

The effects of dehydration are not limited to physical performance; it can also negatively affect cognitive performance [4,5] and various physiological processes such as the cardiovascular and endocrine systems [6,7]. This can lead to decreased athletic performance [8,9,10] and an increased risk of injury [11,12]. In particular, inadequate fluid intake during exercise can significantly decrease athletes’ physical and mental performance [13]. Therefore, athletes must consume adequate fluids before [14], during [15,16], and after exercise [17], and maintain optimal hydration levels throughout the day [6].

As a high-intensity, intermittent team sport, basketball requires players to perform physically demanding movements such as rapid sprints, jumps, sudden changes in direction, and offence–defence transitions [18]. A basketball game can last 32–48 min, depending on the level of play, during which players expend high energy levels [19,20]. Playing in indoor arenas can increase the risk of dehydration due to high temperatures and intense sweating [21]. Therefore, appropriate hydration strategies for basketball players are critical in maintaining performance and preventing injuries.

Hydration needs, sweat rates, and the body’s response to fluid loss may vary by age group. For example, although young athletes have lower sweat rates compared to adults, inadequate fluid consumption habits can increase the risk of dehydration [22]. Similarly, as individuals age, their ability to maintain water balance decreases and their sense of thirst becomes less pronounced, making them more prone to dehydration [23]. In other words, age-related differences in thermoregulation and fluid balance are profound and multifaceted. While children exhibit a lower sweating rate and rely more on dry heat loss through increased skin blood flow (vasodilation) than on evaporative cooling [24,25], the physiological challenges shift considerably in older adulthood.

Compared to young adults, healthy older individuals face a constellation of age-related physiological declines that significantly compromise their ability to manage heat and maintain hydration. Firstly, thermoregulatory efficiency is impaired due to reduced sweat gland output, a delayed onset of sweating, and lower maximal sweat rates, even under comparable heat stress conditions [26,27]. This diminished sweating response severely limits evaporative heat loss. Secondly, renal function declines with age, leading to a reduced urine concentrating ability and an impaired capacity to conserve water during dehydration [28]. This is compounded by endocrine alterations, including a blunted responsiveness to vasopressin (ADH) and changes in the renin–angiotensin–aldosterone system (RAAS), which are critical for fluid and electrolyte homeostasis [29]. Moreover, thirst perception is often blunted in older adults, leading to a delayed or insufficient voluntary fluid intake even when dehydrated [23]. This combination of impaired thermoregulation, diminished renal function, and an attenuated thirst drive markedly increases the vulnerability of people to heat-related illnesses and dehydration with ageing, presenting a distinct contrast to the regulatory profile observed in children.

These findings highlight the need to personalise hydration strategies for athletes of different age groups. However, no studies have specifically compared age-related hydration status in basketball players. While the literature has examined the effect of gender on hydration in high-intensity team sports such as basketball [30] and hydration habits in different sports [31], no studies have focused on age-related hydration differences. Therefore, this study aimed to compare the hydration status of male basketball players in different age groups (i.e., U14 vs. U21) examine the effect of age on hydration, and provide information on this topic to coaches and sports scientists. The findings are believed to guide the development of more effective hydration strategies for young and adult basketball players. This study hypothesises that both the U14 and U21 teams would exhibit optimal hydration status before and after training, and that the U14 team would consume less fluid during training compared to the U21 team.

2. Materials and Methods

2.1. Participants

A total of 70 athletes from U21 (n = 40) and U14 (n = 30) teams of a local basketball club in Kastamonu, Türkiye, voluntarily participated in the study. In the post hoc power analysis conducted using G*Power (Version 3.1.9.7) [32], the groups n = 40 and n = 30, effect size 0.70, and significance 0.05 were entered, and the power (1 − β err prob) was found to be acceptable at 0.88 [33]. The criteria for athletes to participate in the study were as follows: having at least a 3-year basketball experience in competitive basketball, having actively participated in competitions for the past year, participating in regular training at least 3 days a week, and not having experienced any injury that prevented participation in training for the past 6 months. The athletes who used diuretics, medications, or supplements were excluded from the study. The athletes were informed about the study and requested not to use caffeine, alcohol, and diuretics in the 24–72 h prior to the testing, and written consent was obtained from them and/or their legal guardians for participation in the study. Ethical approval for the study was obtained from the Clinical Research Ethics Committee of Kastamonu University on 11 March 2021 with decision number KAEK-143-71. The study was conducted in accordance with the latest version of the Helsinki Declaration.

2.2. Data Collection

Data collection was carried out during the athletes’ preparatory training sessions. The data collection process initially involved anthropometric measurements, collecting urine samples from athletes before and after training, and analysing and monitoring fluid intake during training. Measurements were taken during training sessions conducted at the same time under the same environmental temperature (24.3 ± 1.1 °C). Athletes were not encouraged by the researchers or coaches to consume fluids during the data collection due to the nature of the study.

2.2.1. Anthropometric Measurements

The athletes’ anthropometric measurements included height, body weight, and body fat percentage. When the athletes arrived at the training hall, their heights were measured with a Seca (213, Hamburg, Germany) stadiometer with an accuracy of 0.1 cm. Then, their body weight and body fat percentages were determined using a bioimpedance device (MC-980, TANITA, Tokyo, Japan). The following guidelines were followed to secure accurate and valid electrical bioimpedance results [34].

2.2.2. Hydration Status

Athletes’ hydration status was determined by using urine samples taken before and after training. Athletes were informed on how to provide urine samples before sample collection, and urine containers were distributed. They were then instructed to place their mid-stream [35] urine in a urine container labelled with their name and leave it in the sample collection area before training. All samples were refrigerated and analysed at 20 °C within 8 h [36]. Urine samples were analysed using a digital refractometer (ATAGO, PAL-10S, Tokyo, Japan), and urine specific gravity (USG) was recorded. USG was classified as hydrated (USG < 1.020 g∙mL⁻¹) or hypohydrated (USG ≥ 1.020 g∙mL⁻¹) according to suggestions by the ACSM position stand [37].

2.2.3. Fluid Intake

Bottles filled with water (2 L) were given to each athlete before training, and fluid intake was monitored by researchers during training and recorded in litres.

2.3. Data Analysis

Data were analysed using the JASP software (version 0.18.3.0, Amsterdam, The Netherlands). The normality of the data were checked using the Shapiro–Wilk test and skewness and kurtosis coefficients [38]. Whether the descriptive variables differed between different age groups (U21 and U14) was analysed using an independent samples t-test. Effect size was classified as small (0.20), medium (0.50), or large (0.80) using Cohen’s d obtained from the JASP software package. The change in the USG variable was examined using a repeated measures ANOVA test (2 groups × 2 time points). The mean, standard deviation, and 95% confidence interval (CI) were provided for each variable. The relationship between USG change and fluid intake was examined using Pearson’s correlation test. Statistical significance was set at p < 0.05.

3. Results

The descriptive characteristics of athletes according to age groups are given in

Table 1. Participants’ characteristics.

Variables	Mean ± SD		95% CI
	U21	U14	U21	U14	p	d
Age (years)	21.3 ± 1.2	13.0 ± 0.0	-	-	-	-
Height (m)	1.82 ± 0.10	1.69 ± 0.10	1.79–1.86	1.66–1.74	<0.001	0.280
Body weight (kg)	80.7 ± 13.2	63.4 ± 14.2	76.5–84.9	58.1–68.7	<0.001	0.280
BMI (kg/m2)	24.4 ± 4.5	21.8 ± 3.3	22.8–26.0	20.6–23.1	0.016	0.251
Fat percentage (%)	14.5 ± 6.4	16.1 ± 4.6	12.4–16.5	14.5–17.9	0.224	0.244
Sport experience (years)	9.6 ± 2.2	4.1 ± 1.1	8.9–10.3	3.6–4.5	<0.001	0.418

BMI: body mass index; CI: confidence interval.

.

Table 2. Athletes’ USG values and 95% confidence intervals before and after training.

Group	Mean ± SD		95% CI
	USG Pre-Training	USG Post-Training	USG Pre-Training	USG Post-Training	p (Holm Corrected)
U14	1.020 ± 0.007	1.024 ± 0.006	1.018–1.023	1.024–1.026	0.03
U21	1.020 ± 0.005	1.016 ± 0.008 *	1.019–1.022	1.013–1.019	<0.001

* Holm-corrected, p = 0.03.

presents the USG values of athletes before and after training. The timing of measurements (pre- vs. post-training) did not significantly influence USG changes (F_1,68 = 0.35, p = 0.555, η² = 0.001). However, a significant interaction was observed between measurement time and age group on USG variation (F_1,68 = 23.72, p < 0.001, η² = 0.083). Post hoc analyses with Holm correction revealed that the U14 athletes exhibited a marked increase in post-training USG compared to their pre-training values (p = 0.03). Additionally, the U14 team’s pre-training USG value was significantly higher than the U21 team’s post-training values (p = 0.03). Notably, while the U21 basketball players showed a significant decrease in USG after training (p < 0.001) from their initially elevated pre-training levels, the U14 team demonstrated a substantial rise in USG post-exercise (p < 0.001).

Fluid intake analysis revealed that the U21 team consumed significantly more water (1.16 ± 0.65 L) than the U14 team (0.72 ± 0.50 L) (p = 0.003). The athletes’ hydration status is presented in Figure 1.

Examining the relationship between fluid consumption during training and changes in hydration status revealed no significant correlation in either age group (U14: r = 0.037, p = 0.845; U21: r = 0.162, p = 0.318).

4. Discussion

The present study evaluated and compared hydration status and fluid intake behaviours between U14 and U21 male basketball players during training sessions, revealing significant age-related disparities in hydration practices. The principal findings of the investigation were as follows: First, most U21 athletes initiated training in a dehydrated state, as evidenced by elevated urine specific gravity (USG) values; however, they exhibited effective rehydration strategies during training. Second, U14 players not only commenced training with a poorer hydration status but also experienced further dehydration post-exercise. Third, despite equivalent access to fluids, U14 athletes consumed significantly less fluid (0.72 ± 0.50 L) than their U21 counterparts (1.16 ± 0.65 L, p = 0.003), underscoring a marked age-dependent divergence in voluntary fluid intake.

These findings largely corroborate our initial hypothesis regarding developmental differences in hydration management. The presence of pre-training dehydration in both cohorts suggests systemic deficiencies in daily hydration habits that extend beyond athletic training contexts. Of particular significance is the U21 group’s capacity to improve hydration status during exercise, which may reflect heightened physiological awareness, more mature thirst regulation mechanisms, or accumulated experience with hydration strategies—factors that appear underdeveloped in younger athletes. This distinction is further accentuated by the observation that U14 players exhibited increased dehydration levels following training, a pattern indicative of both insufficient fluid intake and potentially immature thermoregulatory responses.

The current study observed that both U14 and U21 basketball players exhibited pre-training dehydration, as indicated by elevated USG values. These findings align with those of Ceylan [31], who assessed hydration status and fluid intake among adolescent athletes across multiple sports (swimming, judo, basketball, and soccer) during a training day. Ceylan reported that most athletes began training in a dehydrated state and remained so post-exercise, suggesting inadequate habitual hydration practices outside of training. These results closely mirror the present study’s pre- and post-training hydration status of U14 players. Similarly, Arnaoutis et al. [39] examined pre-exercise hydration and fluid intake in young soccer players, noting that athletes arrived at training significantly dehydrated and experienced further fluid deficits despite ad libitum access to fluids. In contrast, while U21 athletes in our study also presented with pre-training dehydration, they demonstrated sufficient fluid intake during exercise, achieving a hydrated state post-training—a behavioural distinction not observed in the U14 cohort.

Deshayes et al. [40] documented a 3.2% reduction in average power output when hydration was suboptimal, further noting that a pre-exercise body weight loss exceeding 3% adversely affects endurance performance. Additional studies have correlated fluid losses equivalent to 2–3% of body weight with diminished sports skill execution [13,41,42]. Specifically, Baker et al. [13] observed that basketball players exhibited reduced shooting frequency and accuracy (particularly in dynamic movements such as layups) at dehydration levels of 3% body weight, with further declines at 4% fluid loss. Despite well-established performance detriments, the persistent finding that athletes routinely initiate training in a dehydrated state highlights a critical disconnect between scientific evidence and practical hydration behaviours. This gap appears especially pronounced among youth athletes, implying that conventional hydration education may be ineffective for adolescent populations. Consequently, comprehensive and result-oriented hydration programmes with close monitoring should be applied to enhance hydration habits of young athletes.

The current study observed significantly lower fluid intake among U14 players compared to U21 athletes. These findings are consistent with those of Horswill et al. [43], who examined sweat rates and voluntary fluid consumption in adolescents and adults exercising at 80–85% of maximal heart rate for one hour under controlled conditions. Without intervention, adults exhibited higher sweat rates and fluid intake than adolescents. Similar trends have been reported elsewhere, with studies indicating that children often fail to consume adequate fluids during exercise unless explicitly instructed to do so [24,44,45]. These collective findings challenge the assertion by the American Academy of Pediatrics [46] that “children generally do not feel the need to consume sufficient fluids to offset losses during prolonged exercise.” Instead, evidence suggests that U14 athletes’ post-training dehydration in the present study likely stems from insufficient voluntary fluid intake. While current guidelines recommend ad libitum fluid consumption based on thirst perception in hot environments [44,47], our results indicate that adults exhibit greater self-regulation in this regard. Thus, tailored hydration education or alternative behavioural strategies may be necessary for younger athletes.

Several methodological limitations should be acknowledged. Although USG serves as a practical hydration marker, its variability and sensitivity to recent fluid intake [48] may influence single-time-point measurements. Incorporating morning USG assessments could strengthen baseline hydration evaluations [49]; however, our pre–post-training design specifically targeted in-session hydration management, a scenario of direct relevance to coaches and sports practitioners. Future research would benefit from 24 h hydration monitoring to better delineate habitual hydration patterns. Moreover, athletes’ body mass change was not monitored pre- and post-training session and it is suggested that this be monitored to assess fluid loss via sweating. Furthermore, athletes were not specifically informed about diet and physical activity in the days pre-testing, which can be taken into account in the future studies to see how their diet and previous physical activity affect their hydration status and fluid intake during a training session.

5. Conclusions

In summary, these findings of the present paper illustrate a developmental progression in hydration management. While both age groups exhibited suboptimal pre-training hydration, only U21 athletes demonstrated the behavioural or physiological capacity to ameliorate fluid deficits during exercise. The progressive dehydration observed in U14 players, coupled with their markedly lower fluid intake, underscores the interplay of physiological immaturity and insufficient hydration awareness in youth athletes. Practical interventions should extend beyond mere fluid availability to incorporate structured education programmes, environmental prompts, and coach-guided hydration protocols, with particular emphasis on adolescent athletes who may lack both the physiological drive and cognitive awareness to hydrate effectively. Such strategies should emphasise both in-training fluid consumption and the importance of sustained 24 h hydration, as pre-training deficits likely originate from broader daily habits rather than isolated training behaviours.