Jesús Cámara

The influence of soccer match play on physiological and physical performance measures in soccer referees and assistant referees

ABSTRACT The aim of this study was to quantify the acute impact of soccer match officiating on selected physiological and physical performance measures. Twenty-four officials from the Spanish National 3rd Division participated in this study. External global positioning system and internal (heart rate) load data were collected for each match official during 8 official matches. Pre- and post-matches, the referees were assessed for tympanic temperature, blood lactate, 15- and 30-m sprint speeds and unilateral (dominant and non-dominant legs) and bilateral vertical jump performances. For referees, the acute physiological and physical performance effects of officiating (post-match value minus pre-match value) were large increases in blood lactate (1.7 mmol · l−1; ±90% confidence limit, 0.9 mmol · l−1; effect size, ES = 4.35), small increases in 15-m sprint (0.09; ±0.04 s; ES = 0.53) and 30-m sprint speeds (0.14; ±0.08 s; ES = 0.39) and a small increase in non-dominant leg jump performance (2.1; ±1.4 cm; ES = 0.31). For assistant referees, there was a small decrease in tympanic temperature (−0.3°C; ±0.2°C; ES = −0.65) and small increases in blood lactate (0.4; ±0.3 mmol · l−1; ES = 0.66), 15-m sprint speed (0.06; ±0.04 s; ES = 0.47), 30-m sprint speed (0.11; ±0.16 s; ES = 0.49) and bilateral countermovement jump height (3.4; ±1.5 cm; ES = 0.45). Taken together, these data demonstrate that the physical demands of soccer officiating are sufficient to elicit increases in blood lactate and small decrements in sprint performance and, thereby, provide some evidence for match-related fatigue.

JUMP LANDING CHARACTERISTICS IN ELITE SOCCER PLAYERS WITH CEREBRAL PALSY

The aim of the present study was to analyse the parameters that characterize the vertical ground reaction force during the landing phase of a jump, and to determine the relationship among these parameters in elite soccer players with cerebral palsy (CP). Thirteen male members of the Spanish national soccer team for people with CP (mean age: 27.1 ± 4.7 years) volunteered for the study. Each participant performed three counter movement jumps. The characteristics of the first peak of the vertical ground reaction force during the landing phase of a jump, which corresponds to the forefoot contact with the ground, were similar to the results obtained in previous studies. However, a higher magnitude of rearfoot contact with the ground (F2) was observed in participants with CP than in participants without CP. Furthermore, a significant correlation between F2 magnitude and the elapsed time until its production (T2) was not observed (r = -0.474 for p = 0.102). This result implies that a landing technique based on a delay in the production of F2 might not be effective to reduce its magnitude, contrary to what has been observed in participants without CP. The absence of a significant correlation between these two parameters in the present study, and the high magnitude of F2, suggest that elite soccer players with CP should use footwear with proper cushioning characteristics.

Effects of horizontal plyometric training volume on soccer players’ performance

ABSTRACT The aim of this study was to examine the dose response effect of strength and conditioning programmes, involving horizontally oriented plyometric exercises, on relevant soccer performance variables. Sixteen soccer players were randomly allocated to two 6-week plyometric training groups (G1 and G2) differing by imposed (twice a week) training volume. Post-training G1 (4.13%; d = 0.43) and G2 (2.45%; d = 0.53) moderately improved their horizontal countermovement jump performance. Significant between-group differences (p < 0.01) in the vertical countermovement jump for force production time (T2) were detected post-training. No significant and practical (p > 0.05, d = trivial or small) post-training improvements in sprint, change of direction ability (CODA) and horizontal arm swing countermovement jump were reported in either group. Horizontal plyometric training was effective in promoting improvement in injury prevention variables. Doubling the volume of a horizontal plyometric training protocol was shown to have no additional effect over functional aspects of soccer players’ performance.

The effect of morphological and functional variables on ranking position of professional junior Basque surfers

Abstract The aim of this study was to analyse the association of morphology as well as functional outcomes during a paddling test with ranking position (RP) of competitive junior surfers. Ten male surfers (age, mean 17.60, s=2.06 years) performed a maximum incremental test on a modified ergometer (Ergo Vasa Swim, USA) to determine, per unit of weight, the relative heart rate at lactate threshold (RHRLT) and at onset of blood lactate accumulation (RHROBLA) and the relative power output at LT (RWLT) and at OBLA (RWOBLA). Anthropometrics were weight, height and sum of six skinfolds (subscapular, triceps, supraspinal, abdominal, anterior thigh and calf) and Heath-Carter anthropometric somatotypes. A stepwise multiple regression was constructed to model and predict RP. Surfers shared a relative short stature and light weight, with a broader range of skinfold thickness (174.30, s=0.07 cm; 66.73, s=5.91 kg; 57.03, s=12.29 mm) and mean somatotype was ectomorphic-mesomorph: 2.20–4.36–3.09 (Category 2). Two model equations were possible: (A) RP = − 244.550 RWOBLA+262.787; (B) RP = − 217.028·RWOBLA+31.21·endomorphy + 169.16 with 63.1% and 83% of variance explained, respectively. A hierarchical cluster analysis on the Euclidean distances of the variables in model B also distinguished between upper and lower ranking groups. RWOBLA was more useful than endomorphy, anthropometric measures and also than the other functional outcomes to predict RPs. RWOBLA and endomorphy should be considered important variables that may influence the success of these young competitive surfers.

INFLUENCE OF PEDALING TECHNIQUE ON METABOLIC EFFICIENCY IN ELITE CYCLISTS

Our objective was to investigate the influence of pedaling technique on gross efficiency (GE) at various exercise intensities in twelve elite cyclists ( · VO2max=75.7 ± 6.2 mL·kg -1 ·min -1 ). Each cyclist completed a · VO2max assessment, skinfold measurements, and an incremental test to determine their lactate threshold (LT) and onset of blood lactate accumulation (OBLA) values. The GE was determined during a three-phase incremental exercise test (below LT, at LT, and at OBLA). We did not find a significant relationship between pedaling technique and GE just below the LT. However, at the LT, there was a significant correlation between GE and mean torque and evenness of torque distribution (r=0.65 and r=0.66, respectively; p < 0.05). At OBLA, as the cadence frequency increased, the GE declined (r=-0.81, p < 0.05). These results suggest that exercise intensity plays an important role in the relationship between pedaling technique and GE.

Differences in Spatiotemporal Parameters Between Trained Runners and Untrained Participants

Abstract Gómez-Molina, J, Ogueta-Alday, A, Stickley, C, Tobalina, JC, Cabrejas-Ugartondo, J, and García-López, J. Differences in spatiotemporal parameters between trained runners and untrained participants. J Strength Cond Res 31(8): 2169–2175, 2017—The aim of this study was to compare the spatiotemporal parameters of trained runners and untrained participants with the same foot strike pattern (rearfoot) during running at controlled speeds. Twenty-one participants were classified in 2 groups according to their training experience: Trained (n = 10, amateur runners with long distance training experience) and Untrained (n = 11, healthy untrained participants). Anthropometric variables were recorded, and the participants performed both a submaximal (between 9 and 15 km·h−1) and a graded exercise running test (from 6 km·h−1 until exhaustion) on a treadmill. Physiological (V[Combining Dot Above]O2max, heart rate, running economy [RE], peak speed …) and biomechanical variables (contact and flight times, step rate, and length) were simultaneously registered. Trained runners showed higher step rate and shorter step length than the Untrained group at the same running speeds (between 4 and 7%, p ⩽ 0.05) and at the same physiological intensities (between 7 and 11%, p ⩽ 0.05). However, there were no differences in contact and flight times between groups. Significant differences (p ⩽ 0.05) and large effect sizes (Cohens d) between groups were found for body mass, sum of 6 skinfolds, V[Combining Dot Above]O2max, peak speed, and ventilatory threshold and respiratory compensation threshold speeds. The Trained group also showed a ∼7% better RE (ml·kg−0.75·km−1) than the Untrained group. In conclusion, adopting higher step rate and shorter step length may be an adaptive mechanism of the Trained group to reduce injury risk and possibly improve RE. However, contact and flight times were consistent regardless of training level.

Bilateral and unilateral vertical ground reaction forces and leg asymmetries in soccer players

The purposes of this study were to assess unilateral and bilateral vertical jump performance characteristics, and to compare the vertical ground reaction force characteristics of the impulse and landing phase of a vertical jump between the dominant and non-dominant leg in soccer players. The sample consisted of 20 male soccer players (22.80 ± 2.71 years, 1.88 ± 0.06 m, 76.47 ± 8.80 kg) who competed in the third division of the Spanish football league. Vertical jump performance was determined by testing the impulse and landing phase of a bilateral vertical jump, dominant leg vertical jump and non-dominant leg vertical jump. Significant differences (p < 0.05) between dominant and non-dominant legs were found in counter movement jump (CMJ) flight time (LA = -2.38%, d = 0.33), CMJ flight height (LA = -4.55%, d = 0.33) and CMJ speed take-off (LA = -2.91%, d = 0.42). No significant differences were found between the dominant and non-dominant leg in the F1 and F2 magnitudes during the landing phase, the time from the first contact of the foot with the ground to the production of F1, the time from the second contact of the foot with the ground to the production of F2, and the time to stabilization of the landing phase. Although differences were found between the dominant and non-dominant leg in the impulse phase of the jump, no significant differences were found between dominant and non-dominant legs in the landing phase of vertical jump variables.

Effects of long-term training cessation in young top-level road cyclists

ABSTRACT In cycling, it is common practice to have a break in the off season longer than 4 weeks while adopting an almost sedentary lifestyle, and such a break is considered to be long-term detraining. No previous studies have assessed the effect of training cessation with highly trained young cyclists. The purpose of the present investigation was to examine effects of 5 weeks of training cessation in 10 young (20.1 ± 1.4 years) male road cyclists for body composition, haematological and physiological parameters. After training cessation, body mass of cyclists increased (P = 0.014; ES = 0.9). (L · min−1 = −8.8 ± 5.0%, mL · kg−1·min−1 = −10.8 ± 4.2%,), Wmax (W = −6.5 ± 3.1%, W · kg−1 = −8.5 ± 3.3%,), WLT1 (W = −12.9 ± 7.0%, W · kg−1 = −14.8 ± 7.4%,), WLT2 (W = −11.5 ± 7.0%, W · kg−1 = −13.4 ± 7.6%,) and haematological (red blood cells count, −6.6 ± 4.8%; haemoglobin, −5.4 ± 4.3% and haematocrit, −2.9 ± 3.0%) values decreased (P ≤ 0.028; ES ≥ 0.9). Five weeks of training cessation resulted in large decreases in physiological and haematological values in young top-level road cyclists suggesting the need for a shorter training stoppage. This long-term detraining is more pronounced when expressed relative to body mass emphasising the influence of such body mass on power output. A maintenance programme based on reduced training strategies should be implemented to avoid large declines in physiological values in young cyclists who aspire to become professionals.

Effects of the off-Season Period on Field and Assistant Soccer Referees `Physical Performance

Abstract The evolution of referees’ physical fitness has been studied over one or several seasons, however, the variation of the physical performance between the end of the competitive season (T1) and the start of the following pre-season (T2) has not been ascertained. Therefore, the aim of this study was to analyze the effects of the transition period on physical performance variables (i.e. linear straight sprint, change of direction ability and endurance) in National Soccer Division referees. Forty-five Spanish referees volunteered to participate in this study. Participants were classified according to competitive status, field referees (FR, n = 23) and assistant referees (AR, n = 22). A loss of performance (p < 0.05) was observed in the 20 and 30 m linear straight sprint between T1 and T2 in both FR (1.64-1.56%, d = 0.29 to 0.32) and AR (2.01-3.41%, d = 0.33 to 0.60). In T2 the FR significantly improved the distance covered (p < 0.05, 13.11%, d = 0.39) in the Yo-Yo Intermittent Recovery test (YYIR1). Besides, significant differences were observed between FR and AR in the distance covered (p < 0.05, −23.55%, d = −0.97) in the YYIR1 test in T2. More research may be necessary to focus on the off-season period in order to implement specific training programs and consequently reduce the loss of sprint ability in field and assistant referees and the decrease in cardiovascular fitness in assistant referees.

The association between physical performance and match-play activities of field and assistants soccer referees

ABSTRACT The aims of this study were to compare the external and internal match responses and fitness performance of national field referees (FRs) and assistant referees (ARs), and to examine the relationships between these fitness measures and physical and physiological responses during match play. Forty-four national soccer match officials (e.g. FRs and ARs) participated in this study. The distance covered and the VO2max in Yo-Yo Intermittent recovery test (YYIR1) and the 30 m sprint test correlated with high speed and high intensity activities during match play in FRs (r = −0.48–0.63, moderate to large, very likely to most likely, p < 0.05). In addition, YYIR1 performance was related to high accelerations (r = 0.41, moderate, likely, p < 0.05) and high decelerations (r = 0.44, moderate, very likely, p < 0.05) for FRs. Better sprint and cardiovascular fitness could be relevant to the performance of FRs during match play.