Introduction

The anthropometric and motor characteristics of athletes are important determinants of successful participation in any given sport. Anthropometric characteristics (including body composition) are closely correlated with motor skills1,2, and they can affect athletes’ motor performance3. An individual’s predisposition to a given sport can be assessed by analyzing his or her anthropometric and motor profiles, depending on body type2,4. Moreover, the acquisition of accurate information regarding the anthropometric and motor status of athletes plays a fundamental role in contemporary sports because a detailed insight into individual athletes’ profiles is needed to design an effective training program and select athletes5. Some anthropometric characteristics, such as length and breadth measurements, are almost exclusively genetically determined and cannot be modified by a training program6. Various anthropometric and motor characteristics are closely linked with successful performance in volleyball5, and these parameters should be assessed for the previously mentioned reasons.

Volleyball has been described as an ‘interval’ sport with both anaerobic and aerobic components5,7. This intermittent sport requires players to compete in frequent short bouts of high-intensity exercise, followed by periods of low-intensity activity8,9,10. Volleyball involves short and frequent explosive activities such as jumping, diving, and ball play11,12,13. High-intensity exercise bouts, coupled with the total duration of the match (approx. 90 min), require players to have well-developed aerobic and anaerobic alactic energy systems14.

The presence of correlations between volleyball players’ reach and performance further justifies the need for research into the anthropometric and motor characteristics of athletes15. Previous studies have reported a strong relationship between motor fitness and playing level, and in volleyball players, fitness typically improved with an increase in playing level5,7,16. Canadian national volleyball team players and Universiade team players had relatively high block (approx. 3.27) and spike (3.43 m) jumps despite similarities in standing and reach height7. Jumping consists of horizontal approach movements (spike jumps, SPJ), as well as movements without an approach that generally involve a countermovement (jump setting, jousts, blocking)11,17. Jumping activities and their frequency during a typical match significantly affect the outcome in volleyball, which is why the players’ ability to perform countermovement vertical jumps (CMVJ) and SPJ are important performance indicators in volleyball7,18. Sheppard et al.19 observed moderate to strong relationships between vertical jump (VJ) performance and strength or power measures in elite volleyball players, which suggests that strength and power qualities influence performance in VJ. However, the relationship between VJ performance and strength or power measures varies across sports and is influenced by athletes’ developmental level20,21,22. In volleyball, the highest reach relative to the maximum value measured in the laboratory was reported for the attack (90.7%), followed by the block and the serve (approx. 89%). The lowest reach was noted for ball setting (77.6%). The average reach in all jumping activities accounted for 87.2% of the maximum value. Furthermore, the highest jumps were observed only in the first set, and the jumps in subsequent sets were lower and fairly similar15. The technical performance of more skilled players may be limited by anthropometric characteristics, motor fitness levels, and performance characteristics such as speed and VJ7.

Time analysis of top men and young male volleyball players

Duration and intensity are the key characteristics of all types of physical effort. There are no official time limits on the length of a volleyball match. The first team to win three sets wins the match23. The length of a match obviously depends on its parts, including the scoring system, rally length (work time during the game), rest time (time between rallies, substitutions, sanctions, technical and team time-outs, time between sets, injuries, and other technical aspects), and the players’ skill24,25. The average duration of a volleyball match is around 100 min26,27,28. Moreover, total work time (time when the ball is in play) is significantly shorter than rest time (35% vs. 65%). Work time during a match and an average set account for a little more than 30% of total time23. Sánchez-Moreno et al.29 classified rally lengths as short (73.6%), medium (15.9%), or long (10.5%). The duration of an average set was determined at 20.44 ± 5.21 min, where the longest set lasted 23.68 min, and the shortest set lasted 18.89 min. It should be noted that in most cases, the highest number of pauses between finished points and the referee’s whistle for the serve lasted more than 10 s (approx. 12 s), but some pause periods lasted more than 20 s, and the number of long pauses was kept at a reasonable level. The duration of finished points in the analyzed matches is worth noting. Most points lasted 5 to 10 s (43.5%), 41% of the points lasted 10–15 s, around 11% of the points lasted 15–20 s, and 3.7% of the points lasted 20–25 s. Active phases of the game tend to increase with the players’ age30. From the practical point of view, it is evident29 that volleyball players consciously take a longer break after a longer active phase, which leads to exhaustion of the nervous and the metabolic system26. Longer times were also registered in a study of top-level male youth volleyball players during the finals and semi-finals of the 2008 Olympic Games (OG08) and four male youth matches during the finals and semi-finals of the 2009 U19 European Youth Championships (YEC09). During OG08 and YEC09 events, the duration of rallies was 5.45 ± 4.77 s and 5.76 ± 4.40 s (ns), respectively; the number of rallies per set was 45.3 ± 5.1 and 44.0 ± 6.7 (ns), respectively; the duration of breaks between rallies was 23.54 ± 5.55 s and 19.99 ± 5.70 s (p < 0.001), respectively; the duration of sets was 1582 ± 133 s and 1412 ± 143 s (p < 0.01), respectively; and the duration of breaks between sets was 217 ± 17 s and 213 ± 20 s (ns), respectively31. These findings indicate that the players’ activity levels and physiological responses during a volleyball game are the main physical challenges associated with playing. Therefore, team volleyball requires not only technical and tactical skills, but also high levels of motor fitness32.

Conditioning is an essential part of any training program, but it is especially important for volleyball players. Effective conditioning helps volleyball players move quickly, jump high, and have the endurance to play for extended periods of time. Conditioning also decreases the risk of injury and fatigue, and it enables volleyball players to perform at their best during games and practices. Various conditioning techniques can be used to help volleyball players improve their strength, speed, agility, and endurance. Some of the most popular types of conditioning for volleyball players include plyometric exercises, aerobic exercises, and strength training. All of these methods can be applied to improve volleyball players’ overall physical fitness and performance on the court. Specificity is one of the key training concepts that should be considered in the process of designing conditioning programs for volleyball players33. Specificity refers to a training approach that focuses on a given set of athletic skills or activities, and it plays a particularly important role in preparing young volleyball players for junior league events. Practical experience indicates that at this stage of training, players are not assigned specific positions, and they work on their motor skills and improve their motor abilities which influence the level of performance success in volleyball.

Similarly to other sports, performance in volleyball is determined by multidisciplinary work, specialized training, and effective planning of training activities at the beginning of the season34. Therefore, diversified strategies and stimuli should be planned for each training stage to enable athletes achieve the desired outcome within a pre-established time35. This process should be divided into several stages which constitute the macrocycles of periodization. Week-long (such as the IMG Academy36 and Volleyball Development Camps37) or even three-day-long (Spire Academy38) sports camps are highly popular, in particular online, and many young volleyball players participate in these events. Based on current evidence, further research is needed to determine whether such short training events make a valuable contribution to the performance of 18-year-old volleyball players. Therefore, the aim of this study was to examine the potential short-term effects of a week-long training camp on the anthropometric and motor characteristics of young adult volleyball players. It was assumed that one week is not a sufficiently long period of time to induce changes in the anthropometric and motor characteristics of 18-year-old volleyball players participating in a sports camp.

Materials and methods

Statement

The research methodology used in this study has been applied in previous studies investigating the effect of thermal stress on the physiological characteristics of young adults, conducted by the authors, whose results have already been published (references − 39,40,41). According to the reviewers, the adopted methods are reliable and the obtained results are objective. Therefore, the research methodology and the presentation of results in this study are similar to those in previous articles by the authors who assume full responsibility for the content and structure of this manuscript.

Participants

The study involved 13 male volleyball right-handed players of the AZS UWM Olsztyn club, aged 17.98 ± 0.51 years (17.6–18.6), who competed in the tournaments of the third national league of the Warmia and Mazury Volleyball Union. The targeted sampling procedure relied on the following inclusion criteria: volleyball players held a valid competition license and had participated in national third league competitions for at least 1 year. All players had valid medical certificates. They trained regularly, and their physical activity levels were not limited (for whatever reason) to the extent that could significantly affect their motor fitness. During a four-week period preceding the first trial, the participants were allowed to miss one training session per week, and none of the participants had been dismissed from training due to illness or injury for more than one week in the previous two months. During the macrocycles, the players trained 12–13 h per week on average. During the volleyball camp, the participants focused on explosive strength training, jumping and plyometrics, efficient power development, and learned correct motor patterns. Total training time during the week-long sports camp was 35 h, and similar amounts of time were dedicated to each training attribute. The participants trained twice daily. The first training session took place between 10 a.m. and 12:30 p.m., and the second training session took place between 5 p.m. and 7:30 p.m. The above training schedule was modified on the following camp days:

  • Days 2 and 5, when the first training session focused on strength and power development. The participants focused on strength in core areas of explosive resistance, jumping and plyometrics, efficient power development, and learned correct motor patterns,

  • On day 3, when the first training session focused mainly on speed and agility. During this session, the participants worked on improving the techniques associated with linear acceleration, maximum velocity, lateral movement, multi-directional movement and agility,

  • On the last day of the camp, the second training session involved a sparring match with a second league volleyball team.

The physical conditioning sub-variables per one training session were as follows: training with weights – 59.9%, power jumps – 6.9%, anaerobic power – 11.3%, flexibility − 9.9%, coordination – 1.9%, postural work – 3.8%, recovery activities − 2.2%, proprioception – 0.5%, aerobic power – 3.6%. The mean dry bulb temperature in daytime was 22.8 ± 2.4 °C during the camp.

Ethics statement

The research was performed in compliance with the guidelines and policies of the Health Science Council and the Declaration of Helsinki, and the study was approved by the Ethics Committee of the University of Warmia and Mazury in Olsztyn (37/2011). Each participant was provided with detailed information about the purpose of the study, potential risks, and the research protocol. The research protocol contained detailed information about measurement methods and motor test techniques that could be practiced during training sessions directly before the study. All volleyball players gave voluntary informed consent to participate in the study by signing consent forms.

Procedures

The first measurement session was conducted two days before the sports camp (15 and 16 August 2022), and the second session was conducted several days after the camp (1 and 2 September 2022). Both sessions took place between 9 a.m. and 11 a.m. under similar environmental conditions. The measurements were performed in the Concept 2 Physical Exercise Laboratory and an indoor sports hall on the campus of the University of Warmia and Mazury in Olsztyn. The players were informed that they could eat a light meal (800–1200 kcal) consisting mainly of carbohydrates (60–70%), but no later than 3–4 h before the trial39.

Anthropometric measurements were performed before motor tests on day 1, and the athletes participated in motor tests on days 1 and 2. The participants were asked not to engage in any strenuous training on the day before the trial. On day 1, the athletes participated in a four-stage reaction time test, a grip strength dynamometer test, and a 5 × 20 s interval motor test on a rowing ergometer directly after anthropometric measurements. On day 2, the subjects participated in VJ, approach jump, and standing long jump motor tests.

Measurements of anthropometric characteristics

Body height was measured to the nearest 1 mm with a calibrated InLab S50 stadiometer (InBody Co, Seoul, South Korea) in accordance with the relevant guidelines. Body mass (measured to the nearest 0.1 kg), the body mass index (BMI, kg/m2), and body composition characteristics, including percent body fat (PBF, %) and skeletal muscle mass (SMM, kg), were determined by bioelectrical impedance with the InBody 270 Bioelectrical Impedance Analyzer (BIA) (Biospace Co. Inc., Seoul, South Korea). The reliability of bioelectrical-impedance analysis relative to other body composition measurement methods, such as DXA, has been successfully demonstrated42,43,44.

Assessment of motor characteristics

Test 1: reaction time test

Reaction time was measured with the Microgate Witty SEM sensor system (Microgate Srl, Bolzano, Italia) composed of 8 LED matrix semaphores that display colors and symbols in different combinations45. Before each test, the participant was positioned in front of the semaphore system. The test began with a 3 s countdown, after which the semaphores were activated. The participant had to follow a test-specific symbol and deactivate the semaphore displaying that symbol by placing his hand over the sensor as quickly as possible. Several sequences of symbols were displayed in succession during the test. Each volleyball player participated in four trials. During each trial, the participant had to identify a given symbol ten times.

Stage 1 (Green): the participant had to respond to a semaphore displaying green light. Only one semaphore was activated at a time.

Stage 2 (Green E): the participant had to respond to the letter "E" displayed in green color. The remaining semaphores displayed other symbols in green color.

Stage 3 (Multicolor): the participant had to respond to a semaphore displaying green light. Other semaphores displayed different colors.

Stage 4 (Multicolor and multisymbol): the participant had to respond to a semaphore displaying the letter "E" in green color. Other semaphores displayed different combinations of symbols and colors.

The participants performed each test once before the camp and once after the camp. In each test, a given symbol was displayed 10 times. The total time between the moment the first symbol was displayed and the moment the last symbol was identified, as well as the times between the symbols were recorded during the test. Only the average scores for the entire test (total time required to perform the test and total for 10 symbols) were presented in a table. Each stage of the test was presented in the same manner.

Test 2: grip strength

Hand grip strength was measured with a handheld hydraulic dynamometer (Charder MG 4800; JAWAG, Bilcza, Poland) to assess maximum voluntary muscle strength. The dynamometer was calibrated before the test to ensure measurement accuracy. The participant was asked to stand in a designated spot with feet hip-width apart. The participant held the dynamometer in the right hand, squeezed it with maximum effort, and maintained that effort for several seconds. The same test was performed in the left hand. The results were expressed in kilograms, as the highest result scored in three trials was recorded.

Test 3: 5 × 20 s interval motor test on a Concept 2 rowing ergometer

The test involved a Concept 2 PM5 standardized rowing ergometer (PH Markus, Szczecin, Poland) which is widely used to measure strength endurance (SE) in athletes46. The rationale behind the rowing ergometer test was to simulate the longest time of an interval exercise corresponding to physical effort during a volleyball game based on the assumption that the rowing interval represents a moment in the game when the ball remains in play and the rest interval represents the end of the playing action and preparation for a serve. Muscle power was assessed in five rowing intervals of 20 s each, interspersed with 20-s rest periods. The following parameters were measured during the rowing ergometer test: maximum, average, and minimum heart rate [HRmax, avg, min]; total distance covered during five 20-s intervals; power generated during the entire test [W]; average rowing time over a distance of 500 m; energy expenditure [kcal] per hour; strokes per minute [SPM, s/m].

The participant wore a Polar H10 heart rate sensor (Polar Electro Oy, Kempele, Finland) on a chest strap. The ergometer was programmed and paired with the ErgData application and the HR sensor. The test was initiated upon a verbal start cue. After each rowing interval of 20 s, the participant rested for 20 s in a sitting position, holding the bar in his hands. The fifth rowing interval was also followed by a 20-s resting period. The data from the ErgData application were recorded in an Excel spreadsheet.

Test 4: Vertical jump

Vertical jump height is typically used as a proxy for leg muscle strength or, more appropriately, leg muscle power47,48. Vertical jump height was measured with a VJ tester. With the feet slightly apart, the subject jumped straight up from a standing position in a movement resembling a volleyball block. At peak height, the participant tapped with the fingers of both hands the highest vane he could reach on the VJ tester. The highest jump reach [cm] from three trials was recorded.

Test 5: Approach jump

Approach jump height was measured with a VJ tester. The participant stood by the tester and raised his arms over his head to mark the maximum standing reach49. The subject then moved several steps away from the tester and, following a short running approach, performed a VJ resembling a volleyball attack. At peak height, the participant tapped with the fingers of one hand the highest vane he could reach on a Vertec VJ tester (Jump USA, Sunnyvale, USA). The subject landed further away from the jump tester, depending on the length of the running approach. The highest jump reach [cm] from three trials was recorded.

Test 6: standing long jump

The standing long jump test began in a standing position with the feet slightly apart and parallel to a take-off line marked on the floor. The participants jumped as far as possible and landed on both feet without falling forward or backward. The perpendicular distance between the heel and the take-off line was measured. The longest distance from three trials was recorded.

Statistical analysis

Basic descriptive statistics (mean, SD, and range) were calculated for each parameter. The normality of data distribution was checked with the Shapiro-Wilk test. All parameters had normal distribution, and the Student’s t-test for dependent samples was used to assess the significance of differences between the arithmetic means of the examined parameters before and after the sports camp. The results were processed in the Statistica v.13. program at a significance level of α = 0.05.

Results

Analysis 1. Changes in anthropometric characteristics

In the group of the examined anthropometric characteristics, a significant decrease was observed in body fat mass (BFM ­ 1.0 kg, p = 0.015), percent body fat (PBF − 1.16%, p = 0.008), and the waist-to-hip ratio (WHR − 0.02, p = 0.001), whereas a significant increase was noted in total body water (TBW + 1.0 L, p = 0.002), proteins (+ 0.33 kg, p = 0.001), minerals (+ 0.12 kg, p = 0.003), fat-free mass (FFM + 1.46 kg, p = 0.001), and skeletal muscle mass (SMM + 0.9 kg, p = 0.001). No significant changes were found in body mass, BMI, or VFL (Table 1).

Table 1 Differences in anthropometric and body composition (A&BC) characteristics before and after the sports camp. Why column headings and results are not centered in the table?
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The segmental analysis of anthropometric and body composition (A&BC) characteristics focused on changes in FFM and BFM (Table 2). No significant differences in FFM and BFM values were noted in the upper limbs (p > 0.05). In the trunk, the mean values of BFM and BFM% were significantly higher before than after the sports camp (difference of 0.57 kg, p = 0.015; difference of 0.28%, p = 0.008, respectively), whereas no significant differences were noted in FFM values. In the lower limbs, a significant increase in FFM (difference of 0.18 kg, p = 0.002), accompanied by a significant decrease in BFM (difference of 0.15 kg, p = 0.020) and BFM% (difference of 0.18%, p = 0.011), were observed in the right leg. A significant increase in FFM (difference of 0.16 km, p = 0.004) and FFM% (difference of 0.11%, p = 0.022), and a significant decrease in BFM% (difference of 0.17%, p = 0.010) were noted in the left leg (Table 2).

Table 2 Changes in FFM and BFM values in the upper limbs, trunk, and lower limbs in the segmental analysis. In my opinion columns’ headings and the results should be centered (excluding the first collumn). Does everything have to be to the left?
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Analysis 2. Changes in motor performance characteristics

The results of psychomotor trials (reaction times) are presented in Table 3. No significant differences in reaction times were observed before and after the sports camp (p > 0.05).

Table 3 Psychomotor abilities before and after the sports camp.
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No significant differences in the parameters evaluated during the 5 × 20 s rowing ergometer test, excluding HR, were noted before and after the sports camp (Table 4). The values of HRavg and HRmax in the 5 × 20 s rowing ergometer test were significantly higher before the sports camp (difference of 10.0 and 17.1 bmp, respectively, p < 0.001 for both).

Table 4 Parameters evaluated in the 5 × 20 s rowing ergometer test before and after the sports camp.
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The results of VJ, approach jump, and standing long jump tests are presented in Table 5. None of the parameters evaluated in the three jump tests differed significantly before and after the sports camp (p > 0.05).

Table 5 The results of vertical jump, approach jump, and standing long jump tests before and after the sports camp.
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In the grip strength dynamometer test (Table 6), significant differences before and after the sports camp were noted in left hand grip strength (increase from 51.46 to 54.08 kg, p = 0.037), but not in right hand grip strength (p > 0.05).

Table 6 The results of the grip strength dynamometer test before and after the sports camp.
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Discussion

The present study was undertaken to determine whether a week-long athletic conditioning camp can contribute to a significant improvement in the anthropometric and motor performance characteristics of young adult volleyball players. After the camp, changes were observed in selected anthropometric characteristics, whereas changes in motor abilities were limited to left hand grip strength.

Changes in anthropometric characteristics

From the practical point of view, changes in body fat mass and muscle mass are the most important parameters in athletes’ anthropometric characteristics. Athletes such as volleyball players benefit from having low body fat, while maintaining or increasing their lean body mass50. In this study, the mean values of FFM and SMM increased, whereas the mean values of BFM, BFP, and VFL decreased after the sports camp. Positive changes were also noted in the values of proteins, minerals, and TBW. These results suggest that a week-long sports camp led to an improvement in volleyball players’ anthropometric characteristics within a relatively short period of time. In a study of 14- to 15-year-old volleyball players, Sieroń et al.51 reported significant changes in individual anthropometric characteristics (sitting height, relaxed arm girth, flexed arm girth, thigh girth, abdomen skinfold thickness, calf skinfold thickness), but not BMI during the entire volleyball season, which was also observed in this study. Anthropometric characteristics (body height, sitting height, relaxed arm girth, flexed arm girth, thigh girth) change dynamically between the ages of 14 and 15, but significant differences in these parameters are unlikely to occur over a period of one week in 18-year-old men whose locomotor system is fully developed52. Caparello et al.53 monitored changes in the anthropometric characteristics of volleyball players aged 19 to 37 years over a period of 8 months, including a pre-season training program, and concluded that proper training combined with an adequate diet induce desirable changes in the body composition characteristics of athletes. These findings corroborate the results of previous studies, where a personalized Mediterranean dietary plan involving monthly changes and adjustments improved the eating habits and health status of elite athletes54,55. In the current study, the sports camp lasted only one week, and dietary recommendations were unlikely to induce significant differences in the participants’ anthropometric characteristics during such a short period of time. For this reason, dietary recommendations were not considered in the study. Mashiko et al.56 evaluated rugby players (mean age − 20.2 years) attending a 20-day conditioning camp and found that camp training led to muscular damage, loss of electrolytes caused by sweating, and changes in immune function. Back players exhibited a higher rate of fat metabolism and electrolyte loss than forwards, possibly because they did more running during the camp. In contrast, forwards experienced more physical contact, performed more physically strenuous exercise, and exhibited higher levels of muscular damage and tissue protein degradation57.

Changes in motor characteristics: practical implications and critical approaches

The results reported by Sheppard et al.12 strongly support the argument that the ability to produce high force and tolerate high tendon tension in rapid stretch-shortening cycle movements is very important for jump performance in volleyball. These skills are most effectively developed during depth-jump training. Practical experience indicates that depth-jump training should be combined with resistance training, in a progression from low to high volumes, under well-monitored conditions, where the performance response (jump height) is measured to guarantee high-quality training and to reduce the risk of injury associated with high-impact activities12,58. Moreover, in elite male volleyball players, improved force, power, and velocity characteristics in unloaded and loaded jump squats are moderately associated with an improvement in jumping ability, and improved depth-jump performance is highly associated with improved jumping ability, such as VJ performance21. Fry et al.18 analyzed the influence of a 12-week, off-season strength and conditioning program on female collegiate volleyball players (mean age − 19.6 ± 0.6 years) of NCAA Division I. The training program included resistance exercises, plyometrics, aerobic endurance exercises, and on-court volleyball practice. The study revealed that most physical and performance variables in starters (ST) and non-starters (NST) improved during the comprehensive strength and conditioning program for female collegiate volleyball players. Volleyball training combined with resistance training led to a greater improvement in both ST and NST. Despite the absence of significant differences between the compared groups, the study demonstrated that in elite players, most performance variables can be improved through comprehensive strength and conditioning training. These observations are consistent with the results of a study conducted on elite Portuguese league volleyball players59 which demonstrated that a 12-week comprehensive strength and conditioning program improved most performance variables in top volleyball players. The cited study revealed that a 12-week training program can improve selected motor abilities in volleyball players59. A 12-week training program (preparatory phase – 8 weeks, competitive phase – 4 weeks) also effectively improved selected anthropometric, physiological, and biochemical parameters in young adult volleyball players (aged 14–30 years) who represented India during various international competitions, including the Junior World Championship and state-level competitions60. Motor abilities generally improve after more than ten weeks of training, and this observation is only partly consistent with the present findings, probably because the Indian training program was 12 times longer than the week-long sports camp analyzed in the current study. Therefore, coaches who are familiar with factors that limit volleyball players’ strength and power can plan sufficiently long strength and conditioning training macrocycles to improve their performance.

The results of the 5 × 20 s interval motor test involving the Concept 2 rowing ergometer were assessed to determine whether a rowing ergometer can be effectively applied in research to evaluate volleyball players’ ability to generate maximum power during repeated efforts that roughly correspond to the duration of a single volleyball action. The rallies lasted 5.0 ± 4.3 s on average, which is why the duration of the interval adopted for the needs of the study (20 s) relates mainly to long rallies that account for only around 10.5% of all rallies during a game29. It was assumed that the participants should also be adequately prepared to play long rallies. In addition to interval duration, the spatial structure of the 5 × 20 s interval test may also be problematic because it does not reflect the type of movements performed during a volleyball game. However, it should be noted that motor fitness is evaluated with the use of specific tests that are applied in various sports disciplines and reflect specific motor skills, as well as tests assessing general motor fitness which also plays an important role during sports training61. The results of general motor fitness tests are used to qualify players, especially young adults (such as juniors), for specialist training62. In professional athletes, endurance is often assessed in a laboratory, but laboratory tests do not account for movements that are specific to a given sports discipline. For example, the Wingate aerobic test on a cycle ergometer is administered to athletes representing different sports disciplines63,64, including volleyball7. In the future, the rowing ergometer test could also be used as an accurate and reliable tool for assessing the performance of substitute players who replace one or more volleyball players on the court for up to several actions. Substitutes should be able to generate maximum power within a relatively short time and score a point (or several points) for the team. Therefore, accurate and reliable interval tests could be applied to maximize the effectiveness of interval training methods in professional volleyball (as an exercise) and to periodically assess training outcomes (as a research tool). Interval tests could also be helpful during functional training of volleyball players to promote motor development and prevent injury caused by repeated movement patterns65,66. For example, cross-training is widely used to structure training programs and improve competitive performance in a given sport through practicing various sports disciplines67,68. However, the criteria for selecting cross-training tests for assessing motor fitness (validity, reliability, objectivity) should be evaluated, the appropriate standards should be developed, and the tests’ potential usefulness for volleyball training should be determined.

An assessment of psychomotor abilities poses a greater challenge. Psychomotor skills deliver numerous benefits by facilitating body schema acquisition, addressing different motor patterns, promoting body control, affirming laterality, developing balance, instilling learning habits, and promoting social integration69,70. Psychomotor training promotes the development of intelligence through motor action, and it constitutes preventive educational action. Coaches should have a good knowledge of psychomotor skills and should foster their development from an early age because psychomotor skills contribute positively to an athlete’s learning71. However, cognitive skills decline with age and are less responsive to training72. Laboratory controlled trials demonstrated that reaction time and movement time increased with fatigue measured by lactate blood levels73,74. According to Mroczek et al.75, 20 h of training per week are sufficient to prevent threshold fatigue levels that significantly decrease psychomotor performance in elite volleyball players.

Smith et al.7 observed significant differences in height, standing reach height, skinfold thickness, lower-body muscular power, agility, and estimated maximal aerobic power among junior volleyball players with different playing abilities, and concluded that the physiological and anthropometric characteristics of players generally improved with an increase in playing level. An athlete’s body type should be considered when allocating resources, selecting playing positions, and conducting conditioning programs to increase the effectiveness of players within a team1. In this study, a week-long training camp induced changes in the anthropometric and body composition characteristics, which suggests that this type of training can also be used to plan the optimal playing positions for 18-year-old volleyball players. At this age, volleyball players should work closely with the coach to determine which playing positions are most likely to maximize their performance on the court.

The significant increase in the grip strength of the left hand, observed after a week-long sports camp, could be due to the fact that all examined volleyball players were right-handed. Therefore, one week of high-intensity physical training could significantly contribute to improving the grip strength of the left hand, which remained less active under standard conditions.

The current study was examined volleyball players were subjected to three times the normal physical load during the week-long sports camp; therefore, it can be assumed that the absence of significant differences in test results is a good predictor of training effectiveness. Perhaps, an excessive training load imposed during a relatively short period of time (one week) led to fatigue, and supercompensation could not be fully achieved before the second trial due to a short regeneration period (3 days)76. However, far-reaching conclusions cannot be formulated at this stage. It appears that week-long training camps could deliver various benefits by promoting team-building and enabling the participants to improve their technical and tactical skills and master various playing strategies (by experimenting with different tactical actions) within a short period of time. During these events, coaches can assess the participants’ progress, performance, motivation, and involvement. Educational and personal growth activities (theoretical courses, workshops, meetings with sports counsellors) during sports camps can help volleyball players prepare both physically and mentally for the season.

Strengths and limitations

To the best of the authors’ knowledge, this is the first study to analyze the potential short-term effects of a week-long training camp on the anthropometric and motor characteristics of young adult volleyball players. The effectiveness of short-term sports camps (including programs lasting several days) has not been investigated to date. The authors are fully aware that the study analyzed a selected group of volleyball players and selected anthropometric and motor characteristics that are essential in this sports discipline. The relatively small number of volleyball players could be considered also a limitation. However, the study relied on longitudinal data, and it involved nearly all team players who trained under identical environmental conditions. It should also be noted that similarly sized samples had been examined in other studies. The participants’ nutritional status and adherence to dietary recommendations were not evaluated, which could also be perceived as a certain limitation. These factors are usually considered when analyzing changes in anthropometric characteristics over relatively longer periods of time. However, as previously indicated, a period of seven days is too short to achieve the desired effects of following dietary recommendations. Future research should also involve blood chemistry tests to measure reliable indicators of fatigue (such as biomarkers of muscular damage), including the acid-base balance and creatine kinase and lactate dehydrogenase levels.

Conclusion

The study demonstrated that a week-long sports camp involving 35 h of training induced significant changes in the anthropometric characteristics of 18-year-old volleyball players. A significant decrease was observed in the values of BFM, PBF, and WHR, whereas a significant increase was noted in the values of TBW, proteins, minerals, FFM, and SMM. However, one week is not long enough to improve motor abilities related to immediate energy generation and explosive strength. One week is also too short to improve psychomotor abilities which, in the light of the cited research, should be conditioned over a period of minimum 12 weeks.