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Balance ist als die koordinative Fähigkeit anzusehen, die am meisten durch das Sinnes- und Nervensystem determiniert ist. Damit könnte sie als Indikator für Funktionseinschränkungen des Nervensystems - etwa bei Lernstörungen - von Wert sein. Aussagen über Zusammenhänge zwischen Balance und Kognition werden vielfach diskutiert, sind jedoch noch nicht hinreichend wissenschaftlich gesichert. Hieraus wird die zentrale Zielstellung der Arbeit abgeleitet, das Wissen über somatische und psychische Determinanten von Balance zu erweitern. Betrachtet werden daher bei Vorschulkindern mögliche Zusammenhänge mit dem Geschlecht, mit den anthropometrischen Parametern Körperhöhe und Fußgröße, mit Statikstörungen des Beckens und der Intelligenzleistung. An der Studie nahmen insgesamt 201 drei- bzw. vierjährige Kinder sowie 148 fünf- bzw. sechsjährige Kinder teil. Die Balancefähigkeit wurde mit Hilfe einer Kraftmomentenplattform sowie eines klinischen Tests erfasst und mit anthropometrischen Parametern, qualitativen statischen Befunden bzw. den Ergebnissen des BIVA-Intelligenztests nach SCHAARSCHMIDT verglichen. Für die Auswertung der Balanceparameter wurden sowohl lineare als auch nichtlineare Verfahren eingesetzt, die zum Teil gegenläufige Trends in Bezug auf Zusammenhänge lieferten. Im Ergebnis konnte ein starker Einfluss des Geschlechts nachgewiesen werden. Mädchen zeigten eine bessere Balanceleistung als Jungen sowohl bei 3-Jährigen als auch bei 6-Jährigen. Dies wird als Beleg für den geschlechtsspezifischen Vorsprung der sensomotorischen Entwicklung bei den Mädchen im Alter von 3 bis 6 Jahren angesehen. Außerdem gab es einige Hinweise auf einen Zusammenhang mit der Körperhöhe bzw. Fußlänge. Ein Zusammenhang mit den Umstellungen des ersten Gestaltwandels wird vermutet. Die Daten sprechen für einen statistisch schwachen Einfluss von Störungen der Beckenstatik (Beckenverwringung) auf die Balance bei den Kindern. Es wird vermutet, dass die Verrechnung Balance relevanter Inputs durch nozizeptive Impulse beeinträchtig werden kann. Dies könnte Anlass sein, diesen Aspekt bei Funktionsstörungen mit zu berücksichtigen. Signifikante Zusammenhänge mit Ergebnissen des BIVA-Intelligenztests konnten kaum gefunden werden. Allerdings fallen überzufällig viele Mittelwertvergleiche in Richtung der Hypothese aus, erreichen jedoch nicht Signifikanzniveau. Dies könnte ein Hinweis auf einen schwachen Zusammenhang darstellen, der jedoch mit einer größeren Gruppe noch bestätigt werden müsste. Weitere Forschung auf diesem Gebiet ist erforderlich. Sollte hinreichende Evidenz erreicht werden können, so könnte in der Förderung koordinativer Fähigkeiten und insbesondere der posturalen Balance eine wichtige pädagogische Reserve liegen.
The integration of balance and plyometric training has been shown to provide significant improvements in sprint, jump, agility, and other performance measures in young athletes. It is not known if a specific within session balance and plyometric exercise sequence provides more effective training adaptations. The objective of the present study was to investigate the effects of using a sequence of alternating pairs of exercises versus a block (series) of all balance exercises followed by a block of plyometric exercises on components of physical fitness such as muscle strength, power, speed, agility, and balance. Twenty-six male adolescent soccer players ( 13.9 +/- 0.3 years) participated in an 8-week training program that either alternated individual balance (e. g., exercises on unstable surfaces) and plyometric (e. g., jumps, hops, rebounds) exercises or performed a block of balance exercises prior to a block of plyometric exercises within each training session. Pre- and post-training measures included proxies of strength, power, agility, sprint, and balance such as countermovement jumps, isometric back and knee extension strength, standing long jump, 10 and 30-m sprints, agility, standing stork, and Y-balance tests. Both groups exhibited significant, generally large magnitude (effect sizes) training improvements for all measures with mean performance increases of approximately > 30%. There were no significant differences between the training groups over time. The results demonstrate the effectiveness of combining balance and plyometric exercises within a training session on components of physical fitness with young adolescents. The improved performance outcomes were not significantly influenced by the within session exercise sequence.
Coordination of the trunk and hips is crucial for successful dynamic balance in many activities of daily living. Persons with recurrent low back pain (rLBP), both while symptomatic and during periods of symptom remission, exhibit dysfunctional muscle activation patterns and coordination of these joints. In a novel dynamic balance task where persons in remission from rLBP exhibit dissociated trunk motion, it is unknown how trunk and hip musculature are coordinated. Activation of hip and trunk muscles were acquired from nineteen persons with and without rLBP during the Balance-Dexterity Task, which involves balancing on one limb while compressing an unstable spring with the other. There were no between-group differences in activation amplitude for any muscle groups tested. In back-healthy control participants, hip and trunk muscle activation amplitudes increased proportionally in response to the added instability of the spring (R = 0.837, p < 0.001). Increases in muscle activation amplitudes in the group in remission from rLBP were not proportional (R = 0.113, p = 0.655). Instead, hip muscle activation in this group was associated with task performance, i.e. dexterous control of the spring (R = 0.676, p = 0.002). These findings highlight atypical coordination of hip and trunk musculature potentially related to task demands in persons with rLBP even during remission from pain.
The purpose of this study was to investigate the effects of plyometric training on stable (SPT) vs. highly unstable surfaces (IPT) on athletic performance in adolescent soccer players. 24 male sub-elite soccer players (age: 15 +/- 1 years) were assigned to 2 groups performing plyometric training for 8 weeks (2 sessions/week, 90min each). The SPT group conducted plyometrics on stable and the IPT group on unstable surfaces. Tests included jump performance (countermovement jump [CMJ] height, drop jump [DJ] height, DJ performance index), sprint time, agility and balance. Statistical analysis revealed significant main effects of time for CMJ height (p<0.01, f=1.44), DJ height (p<0.01, f=0.62), DJ performance index (p<0.05, f=0.60), 0-10-m sprint time (p<0.05, f=0.58), agility (p<0.01, f=1.15) and balance (p<0.05, 0.46f1.36). Additionally, a Training groupxTime interaction was found for CMJ height (p<0.01, f=0.66) in favor of the SPT group. Following 8 weeks of training, similar improvements in speed, agility and balance were observed in the IPT and SPT groups. However, the performance of IPT appears to be less effective for increasing CMJ height compared to SPT. It is thus recommended that coaches use SPT if the goal is to improve jump performance.
Background and objectives: Age-related losses of lower extremity muscle strength/power and deficits in static and particularly dynamic balance are associated with impaired functional performance and the occurrence of falls. It has been shown that balance and resistance training have the potential to improve balance and muscle strength in healthy older adults. However, it is still open to debate how the effectiveness of balance and resistance training in older adults is influenced by different factors. This includes the role of trunk muscle strength, the comprehensive effects of combined balance and resistance training, and the role of exercise supervision. Therefore, the primary objectives of this doctoral thesis are to investigate the relationship between trunk muscle strength and balance performance and to examine the effects of an expert-based balance and resistance training protocol on various measures of balance and lower extremity muscle strength/power in older adults. Furthermore, the impact of supervised versus unsupervised balance and/or resistance training interventions in the elderly will be evaluated.
Methods: Healthy older adults aged 63-80 years were included in a cross-sectional study, a longitudinal study, and a meta-analysis (range group means meta-analysis: 65.3-81.1 years) registering balance and muscle strength/power performance. Different measures of balance (i.e., static/dynamic, proactive, reactive) were examined using clinical (e.g., Romberg test) and instrumented tests (e.g., 10 meter walking test on a sensor-equipped walkway). Isometric strength of the trunk muscles was assessed using instrumented trunk muscle strength apparatus and lower extremity dynamic muscle strength/power was examined using clinical tests (e.g., Chair Stand Test). Further, a combined balance and resistance training protocol was applied to examine training-induced effects on balance and muscle strength/power as well as the role of supervision in older adults.
Results: Findings revealed that measures of trunk muscle strength and static steady-state balance as well as specific measures of dynamic steady-state balance were significantly associated in the elderly (0.42 ≤ r ≤ 0.57). Combined balance and resistance training significantly improved older adults' static/dynamic steady-state (e.g., Romberg test; habitual gait speed), pro-active (e.g., Timed Up and Go Test), and reactive balance (e.g., Push and Release Test) as well as muscle strength/power (e.g., Chair Stand Test) (0.62 ≤ Cohen’s d ≤ 2.86; all p < 0.05). Supervised compared to unsupervised balance and/or resistance training was superior in enhancing older adults' balance and muscle strength/power performance regarding all observed outcome categories [longitudinal study: effects for the supervised group 0.26 ≤ d ≤ 2.86, effects for the unsupervised group 0.06 ≤ d ≤ 2.30; meta-analysis: all between-subject standardized mean differences (SMDbs) in favor of the supervised training programs 0.24-0.53]. The meta-analysis additionally showed larger effects in favor of supervised interventions when compared to completely unsupervised interventions (0.28 ≤ SMDbs ≤ 1.24). These effects in favor of the supervised programs faded when compared with studies that implemented a small amount of supervised sessions in their unsupervised interventions (−0.06 ≤ SMDbs ≤ 0.41).
Conclusions: Trunk muscle strength is associated with steady-state balance performance and may therefore be integrated in fall-preventive exercise interventions for older adults. The examined positive effects on a large number of important intrinsic fall risk factors (e.g., balance deficits, muscle weakness) imply that particularly the combination of balance and resistance training appears to be a feasible and effective exercise intervention for fall prevention. Owing to the beneficial effects of supervised compared to unsupervised interventions, supervised sessions should be integrated in fall-preventive balance and/or resistance training programs for older adults.
Vegetation with an adequate supply of water might contribute to cooling the land surface around it through the latent heat flux of transpiration. This study investigates the potential estimation of evaporative cooling at plot scale, using soybean as example. Some of the plants' physiological parameters were monitored and sampled at weekly intervals. A physics-based model was then applied to estimate the irrigation-induced cooling effect within and above the canopy during the middle and late season of the soybean growth period. We then examined the results of the temperature changes at a temporal resolution of ten minutes between every two irrigation rounds. During the middle and late season of growth, the cooling effects caused by evapotranspiration within and above the canopy were, on average, 4.4 K and 2.9 K, respectively. We used quality indicators such as R-squared (R-2) and mean absolute error (MAE) to evaluate the performance of the model simulation. The performance of the model in this study was better above the canopy (R-2 = 0.98, MAE = 0.3 K) than below (R-2 = 0.87, MAE = 0.9 K) due to the predefined thermodynamic condition used to estimate evaporative cooling. Moreover, the study revealed that canopy cooling contributes to mitigating heat stress conditions during the middle and late seasons of crop growth.
Power training programs have proved to be effective in improving components of physical fitness such as speed. According to the concept of training specificity, it was postulated that exercises must attempt to closely mimic the demands of the respective activity. When transferring this idea to speed development, the purpose of the present study was to examine the effects of resisted sprint (RST) vs. traditional power training (TPT) on physical fitness in healthy young adults. Thirty-five healthy, physically active adults were randomly assigned to a RST (n = 10, 23 ± 3 years), a TPT (n = 9, 23 ± 3 years), or a passive control group (n = 16, 23 ± 2 years). RST and TPT exercised for 6 weeks with three training sessions/week each lasting 45–60 min. RST comprised frontal and lateral sprint exercises using an expander system with increasing levels of resistance that was attached to a treadmill (h/p/cosmos). TPT included ballistic strength training at 40% of the one-repetition-maximum for the lower limbs (e.g., leg press, knee extensions). Before and after training, sprint (20-m sprint), change-of-direction speed (T-agility test), jump (drop, countermovement jump), and balance performances (Y balance test) were assessed. ANCOVA statistics revealed large main effects of group for 20-m sprint velocity and ground contact time (0.81 ≤ d ≤ 1.00). Post-hoc tests showed higher sprint velocity following RST and TPT (0.69 ≤ d ≤ 0.82) when compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to 4.5% for RST [90%CI: (−1.1%;10.1%), d = 1.23] and 2.6% for TPT [90%CI: (0.4%;4.8%), d = 1.59]. Additionally, ground contact times during sprinting were shorter following RST and TPT (0.68 ≤ d ≤ 1.09) compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to −6.3% for RST [90%CI: (−11.4%;−1.1%), d = 1.45) and −2.7% for TPT [90%CI: (−4.2%;−1.2%), d = 2.36]. Finally, effects for change-of-direction speed, jump, and balance performance varied from small-to-large. The present findings indicate that 6 weeks of RST and TPT produced similar effects on 20-m sprint performance compared with a passive control in healthy and physically active, young adults. However, no training-related effects were found for change-of-direction speed, jump and balance performance. We conclude that both training regimes can be applied for speed development.
Power training programs have proved to be effective in improving components of physical fitness such as speed. According to the concept of training specificity, it was postulated that exercises must attempt to closely mimic the demands of the respective activity. When transferring this idea to speed development, the purpose of the present study was to examine the effects of resisted sprint (RST) vs. traditional power training (TPT) on physical fitness in healthy young adults. Thirty-five healthy, physically active adults were randomly assigned to a RST (n = 10, 23 ± 3 years), a TPT (n = 9, 23 ± 3 years), or a passive control group (n = 16, 23 ± 2 years). RST and TPT exercised for 6 weeks with three training sessions/week each lasting 45–60 min. RST comprised frontal and lateral sprint exercises using an expander system with increasing levels of resistance that was attached to a treadmill (h/p/cosmos). TPT included ballistic strength training at 40% of the one-repetition-maximum for the lower limbs (e.g., leg press, knee extensions). Before and after training, sprint (20-m sprint), change-of-direction speed (T-agility test), jump (drop, countermovement jump), and balance performances (Y balance test) were assessed. ANCOVA statistics revealed large main effects of group for 20-m sprint velocity and ground contact time (0.81 ≤ d ≤ 1.00). Post-hoc tests showed higher sprint velocity following RST and TPT (0.69 ≤ d ≤ 0.82) when compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to 4.5% for RST [90%CI: (−1.1%;10.1%), d = 1.23] and 2.6% for TPT [90%CI: (0.4%;4.8%), d = 1.59]. Additionally, ground contact times during sprinting were shorter following RST and TPT (0.68 ≤ d ≤ 1.09) compared to the control group, but no difference between RST and TPT. Pre-to-post changes amounted to −6.3% for RST [90%CI: (−11.4%;−1.1%), d = 1.45) and −2.7% for TPT [90%CI: (−4.2%;−1.2%), d = 2.36]. Finally, effects for change-of-direction speed, jump, and balance performance varied from small-to-large. The present findings indicate that 6 weeks of RST and TPT produced similar effects on 20-m sprint performance compared with a passive control in healthy and physically active, young adults. However, no training-related effects were found for change-of-direction speed, jump and balance performance. We conclude that both training regimes can be applied for speed development.
This study aimed at examining the effects of plyometric training on stable (SPT) vs. unstable (UPT) surfaces on physical fitness in prepuberal soccer players. Male athletes were randomly assigned to SPT (n = 18; age = 12.7 +/- 0.2 years) or UPT (n = 16; age = 12.2 +/- 0.5 years). Both groups conducted 3 regular soccer training sessions per week combined with either 2 SPT or UPT sessions. Assessment of jumping ability (countermovement jump [CMJ], and standing long jump [SLJ]), speed (10-m, 20-m, 30-m sprint), agility (Illinois agility test [IAT]), and balance (stable [SSBT], unstable [USBT] stork balance test; stable [SYBT], unstable [UYBT] Y balance test) was conducted pre-and post-training. An ANCO-VA model was used to test for between-group differences (SPT vs. UPT) at post-test using baseline values as covariates. No significant differences were found for CMJ height (p > 0.05, d = 0.54), SLJ (p > 0.05; d = 0.81), 10-m, 20-m, and 30-m sprint performances (p > 0.05, d = 0.00-0.24), IAT (p > 0.05, d = 0.48), and dynamic balance (SYBT and UYBT, both p > 0.05, d = 0.39, 0.08, respectively). Statistically significant between-group differences were detected for the USBT (p < 0.01, d = 1.86) and the SSBT (p < 0.01, d = 1.75) in favor of UPT. Following 8 weeks of SPT or UPT in prepuberal athletes, similar performance levels were observed in both groups for measures of jumping ability, speed, dynamic balance, and agility. However, if the goal is to additionally enhance static balance, UPT has an advantage over SPT.
Previous studies contrasted the effects of plyometric training (PT) conducted on stable vs. unstable surfaces on components of physical fitness in child and adolescent soccer players. Depending on the training modality (stable vs. unstable), specific performance improvements were found for jump (stable PT) and balance performances (unstable PT). In an attempt to combine the effects of both training modalities, this study examined the effects of PT on stable surfaces compared with combined PT on stable and unstable surfaces on components of physical fitness in prepuberal male soccer athletes. Thirty-three boys were randomly assigned to either a PT on stable surfaces (PTS; n = 17; age = 12.1 +/- 0.5 years; height = 151.6 +/- 5.7 cm; body mass = 39.2 +/- 6.5 kg; and maturity offset = 22.3 +/- 0.5 years) or a combined PT on stable and unstable surfaces (PTC; n = 16; age = 12.2 +/- 0.6 years; height = 154.6 +/- 8.1 cm; body mass = 38.7 +/- 5.0 kg; and maturity offset = 22.2 +/- 0.6 years). Both intervention groups conducted 4 soccer-specific training sessions per week combined with either 2 PTS or PTC sessions. Before and after 8 weeks of training, proxies of muscle power (e.g., countermovement jump [CMJ], standing long jump [SLJ]), muscle strength (e.g., reactive strength index [RSI]), speed (e.g., 20-m sprint test), agility (e.g., modified Illinois change of direction test [MICODT]), static balance (e.g., stable stork bal-ance test [SSBT]), and dynamic balance (unstable stork balance test [USBT]) were tested. An analysis of covariance model was used to test between-group differences (PTS vs. PTC) at posttest using baseline outcomes as covariates. No significant between-group differences at posttest were observed for CMJ (p > 0.05, d = 0.41), SLJ (p > 0.05, d = 0.36), RSI (p > 0.05, d = 0.57), 20-m sprint test (p > 0.05, d = 0.06), MICODT (p > 0.05, d = 0.23), and SSBT (p > 0.05, d = 0.20). However, statistically significant between-group differences at posttest were noted for the USBT (p < 0.01, d = 1.49) in favor of the PTC group. For most physical fitness tests (except RSI), significant pre-to-post improvements were observed for both groups (p < 0.01, d = 0.55-3.96). Eight weeks of PTS or PTC resulted in similar performance improvements in components of physical fitness except for dynamic balance. From a performance-enhancing perspective, PTC is recommended for pediatric strength and conditioning coaches because it produced comparable training effects as PTS on proxies of muscle power, muscle strength, speed, agility, static balance, and additional effects on dynamic balance.