Mobility of symmetric deployable structures subjected to external loads

As a multidisciplined combat sport, relationships between external and internal training loads and intensities of mixed martial arts (MMA) have not been described. The aim of this study was to determine the external loads and intensities of MMA training categories and their relationship to internal loads and intensities. Twenty MMA athletes (age = 23.3 [5.3] y, mass = 72.1 [7.2]kg, stature = 171.5 [8.4]cm) were observed for 2 consecutive weeks. Internal load and intensity (session rating of perceived exertion [sRPE]) were calculated using the Foster RPE for the session overall (sRPE-training load [TL]) and segmented RPE (segRPE-TL) for each training category: warm-up, striking drills, wrestling drills, Brazilian jiujitsu (BJJ) drills, striking sparring, wrestling sparring, BJJ sparring, and MMA sparring. External load and intensity were measured via Catapult OptimEye S5 for the full duration of each session using accumulated Playerload (PLdACC) and PLdACC per minute (PLdACC·min-1). Differences in loads between categories and days were assessed via Bayesian analysis of variance (BF10 ≥ 3). Predictive relationships between internal and external variables were calculated using Bayesian regression. Session overall sRPE-TL = 448.6 (191.1)arbitrary units (AU); PLdACC = 310.6 (112)AU. Category segRPE-TL range = 33.8 (22.6)AU (warm-up) to 122.8 (54.6)AU (BJJ drills). Category PLdACC range = 44 (36.3)AU (warm-up) to 125 (58.8)AU (MMA sparring). Neither sRPE-TL nor PLdACC changed between days. PLdACC was different between categories. Evidence for regressions was strong-decisive except for BJJ drills (BF10 = 7, moderate). R2 range = .50 to .77, except for warm-up (R2 = .17), BJJ drills (R2 = .27), BJJ sparring (R2 = .49), and session overall (R2 = .13). While MMA training categories may be differentiated in terms of external load, overall session external load does not change within or between weeks. Resultant regression equations may be used to appropriately plan MMA technical/tactical training loads.

Training load is typically described in terms of internal and external load. Investigating the coupling of internal and external training load is relevant to many sports. Here, continuous kernel-density estimation (KDE) may be a valuable tool to capture and visualize this coupling. Using training load data in speed skating, we evaluated how well bivariate KDE plots describe the coupling of internal and external load and differentiate between specific training sessions, compared to training impulse scores or intensity distribution into training zones. On-ice training sessions of 18 young (sub)elite speed skaters were monitored for velocity and heart rate during 2 consecutive seasons. Training session types were obtained from the coach's training scheme, including endurance, interval, tempo, and sprint sessions. Differences in training load between session types were assessed using Kruskal-Wallis or Kolmogorov-Smirnov tests for training impulse and KDE scores, respectively. Training impulse scores were not different between training session types, except for extensive endurance sessions. However, all training session types differed when comparing KDEs for heart rate and velocity (both P < .001). In addition, 2D KDE plots of heart rate and velocity provide detailed insights into the (subtle differences in) coupling of internal and external training load that could not be obtained by 2D plots using training zones. 2D KDE plots provide a valuable tool to visualize and inform coaches on the (subtle differences in) coupling of internal and external training load for training sessions. This will help coaches design better training schemes aiming at desired training adaptations.

Konarski, JM, Konarska, A, Strzelczyk, R, Skrzypczak, M, and Malina, RM. Internal and external loads during Hockey 5's competitions among U16 players. J Strength Cond Res 35(11): 3199-3206, 2021-The purpose of the study was to characterize the external and internal loads associated with Hockey 5's, the modified small-sided format of competition for U16 field hockey introduced in 2014. Subjects were 10 males, 15.2-16.3 years, who were field players on the U16 Polish National Team. A GPSports Athlete Tracking System was used to estimate external loads (sprints, total distance), and a Polar Team2 unit was used to monitor internal loads (heart rate [HR] and energy expenditure [EE]) during active time of play for 8 field players in 2 international matches. Players covered, on average, a distance of 2,217 ± 178 m during a match including 614 ± 12 m sprinting at 8.1 ± 0.8 km·h-1 with a speedmax of 23.1 ± 1.1 km·h-1. HRmean was 170.5 ± 6.6 b·min-1, whereas HRmax was 184.9 ± 6.4 b·min-1. Speed, sprinting, and distance covered did not differ among periods, whereas HR was greater during the second and third periods. HRmax, %HRmax, and EE varied between forwards and defenders, and among periods. Effort expended by field players during Hockey 5's games can be characterized as heavy. The results highlight the need for preparation in both aerobic and anaerobic activities, which include a major speed component and adequate time for rapid recovery to facilitate the adaptation of youth players to the demands of the modified game. Although not directly comparable, comparison of internal loads during Hockey 5's and 11-a-side matches suggests more intensive activity of field players in the former.

Kinematic of symmetric deployable scissor-hinge structures with integral mechanism mode

The efficiency index (Effindex) combines internal and external loads, and it has been considered a promising tool to evaluate physical fitness status. However, its real applicability and limitations have not been elucidated yet. To examine and discuss the findings from studies that used Effindex as a tool for the evaluation of physical fitness status in team sports. A systematic search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases conferred were PubMed, Scopus, Web of Science, SPORTDiscus, MEDLINE and CINAHL. The articles selected were published up to March 2021. Fourteen articles were included after meeting the inclusion criteria. A wide variety of combinations of external and internal loading parameters to calculate Effindex were found. The pooled sample included 349 male participants (23 ± 3 years). Fifty-nine percent of the sample were soccer players, 20% rugby players, 10% Australian football players, 7% hurling players, and 4% basketball players. Most Effindex calculations used total distance (TD) divided by heart rate derived parameters. However, recent studies have suggested the use of accelerations as the external load parameter. Effindex is a simple and powerful tool for the evaluation of physical fitness status in team sports athletes. The disparity of external and internal loading parameters used to calculate Effindex may affect its sensitivity to detect changes in fitness status in different team sport settings. More studies with indoor team sports and female athletes are warranted.

The present study aimed to assess and compare the internal and external training loads experienced by elite young female football players during small-sided games (SSGs) conducted on two different pitch sizes. Eight athletes (age: 19.6 ± 3.7 years) from a top-tier Greek women’s football team participated in two training sessions and one official match. GPS tracking and heart rate monitoring were used to collect data on total distance, speed zones, sprint count, maximum speed, and heart rate distribution across five intensity zones. Two SSG formats (4v4) were implemented: one on a 20×30 m pitch (75 m²/player) and one on a 30×40 m pitch (150 m²/player), each consisting of four 4-minute bouts with 2-minute passive recovery. The results revealed no significant differences in internal load (heart rate responses) between the two pitch sizes. However, external load metrics varied notably: the smaller pitch induced more frequent accelerations and decelerations (p &lt; .05), while the larger pitch resulted in longer total distances and more sprints (p &lt; .05). These findings highlight the influence of pitch size on movement demands, with smaller areas favouring anaerobic, change-of-direction actions and larger areas promoting mostly aerobic and high-speed activities. The study emphasizes the effectiveness of SSGs in conditioning programs and supports their role in developing both aerobic and anaerobic fitness within realistic game contexts. The application of GPS technology enabled precise workload quantification, offering valuable insights for individualized training design. Importantly, this research addresses a gap in the literature regarding elite young women footballers, providing practical guidance for coaches aiming to optimize performance and minimize injury risk through targeted SSG configurations.

To examine the internal and external load imposed by long sprint ability-oriented small-sided games (SSG) using different ratios of players to pitch area (densities) in soccer players. A total of 19 professional soccer players from the same soccer club (age = 17.1 [0.3]y, height = 1.76 [0.69]m, and body mass = 69.7 [9.4]kg) participated in this study. Players performed 4 × 30-s (150s recovery) all-out 1-vs-1 SSG considering 300, 200, and 100m2 per player (48h apart). Players' external loads were tracked with global positioning technology (20Hz). Heart rate, blood lactate concentration (BLc), and rating of perceived exertion characterized players' internal load. Peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT). SSG300 produced higher BLc than SSG200 (moderate) and SSG100 (large). The SSG300, SSG200, and SSG100 BLc were 97.8% (34.8%), trivial; 74.7% (24.9%), moderate; and 43.4% (15.7%), large, of the NMT30s peak BLc, respectively. Players covered more distance at high intensity during the SSG300 than in other SSG conditions (huge to very large differences). High-intensity deceleration distance was largely lower in SSG200 than in SSG300. SSG100 elicited very large to huge and large to very large lower external load values than SSG300 and SSG200, respectively. The main finding of this study showed an inverse association between ball-drill density and internal/external loads in long sprint ability-oriented SSG. The SSG300 provided BLc closer to individual maximal, thus satisfying the all-out construct assumed for the development of long sprint ability. Further studies using the SSG300 as a training intervention and/or investigating other different SSG formats using the same density are warranted.

Lake Rotorua is one of 12 lakes jointly managed by the Rotorua Lakes Council, Te Arawa Lakes Trust and the Bay of Plenty Regional Council under the Rotorua Te Arawa Lakes Programme. The lake is currently classified as eutrophic and a Trophic Lake Index (TLI) value of 4.2 has been set as an integrated target for lake water quality. A number of catchment and lake management strategies have been implemented to achieve the targeted TLI including land use changes, wetland enhancement, lake weed harvesting, sediment detainment bunds, sewage reticulation and alum dosing. Alum (aluminium sulphate) is commonly applied to freshwater and wastewater systems to remove phosphorus, reducing its availability for phytoplankton growth. The initiation of alum dosing to the Utuhina Stream in 2006 and the Puarenga Stream in 2010 was associated with a significant decline in water column dissolved reactive phosphorus (DRP) and improvements in water quality of Lake Rotorua. The use of alum to control external and internal phosphorus loading has been identified as key component in the restoration of Lake Rotorua and recently observed improvements in water quality suggest that the lake could be transitioning to a more phosphorus limited state. Determination of phytoplankton nutrient limitation in Lake Rotorua was identified as a priority through the 2017 Plan Change 10 Science Review. An initial seasonal nutrient limitation study was carried out in 2019 with nutrient limitation assays conducted at 3-monthly intervals over the course of the year. Nitrogen limitation was indicated for the March assay and nutrient co-limitation for the December period, but results for the winter and spring periods were inconclusive. There has also been increasing recognition that nutrient availability in limnetic systems may vary in response to seasonal changes in external and external loading and even to isolated storm events. The University of Waikato was contracted to investigate potential changes in nutrient limitation within Lake Rotorua at sub-monthly time-scales, and to determine if alum dose rates could be optimised to take advantage of periods of phosphorus limitation. Phytoplankton nutrient limitation growth assays were conducted on a fortnightly basis from mid-October 2020 to May 2021. In addition to determination of lake surface nutrient and chlorophyll a concentrations, triplicate 1 L phytoplankton samples were spiked with either phosphorus (0.1 mg-P L⁻¹), nitrogen (1 mg-N L⁻¹) or phosphorus (0.1 mg-P L⁻¹) and nitrogen (1 mg-N L⁻¹) and incubated for 5-days under a single light intensity of 100 μmol m⁻²s⁻¹ PAR at lake surface temperature and photoperiod. Phytoplankton growth responses were measured as comparative chlorophyll a, comparative biomass and net biomass growth. Summarised results from the 16 assays along with the predicted nutrient state from the stoichiometric mass ratio of TN:TP are presented in the table below. Under the test conditions nitrogen limitation was indicated for most of the summer months (December–March) and nutrient co-limitation during the spring and late autumn. Only short (~2 weeks) periods of P-limitation were observed, one of which was associated with an intensive storm event at the end of March. These seasonal fluctuations in nitrogen and phosphorus supply are similar to those observed in other temperate limnetic systems. In the spring, external nitrogen and phosphorus loading is high, then decline in the summer as rainfall and associated inflows wane. During the summer, internal loading becomes more important in polymictic lakes due to repeated internal nutrient cycling from stratification and mixing events. This results in phosphorus limitation in the spring, transitioning to nitrogen limitation or colimitation (primarily nitrogen) in the summer, and then returning to phosphorus/colimitation during the winter due to increased nitrogen-loading from the catchment from increased catchment discharge. Due to the modest periods of phosphorus limitation indicated by the assays, there appears to be little potential for optimisation of alum dose rates in order capitalise on natural periods of phosphorus limitation. Further, changes in phytoplankton community composition and abundance appear to be more strongly driven by physical environmental factors such as temperature, light and wind speed, than nutrient availability. Although alum dosing is effective in removing DRP from the Utuhina and Puarenga inflows, its assumed effectiveness in reducing internal phosphorus loading in Lake Rotorua requires further evaluation.

Load management and optimising performance in elite sport. External and internal loads during team handball training and matches were examined in professional highly training male team handball players (n = 13) over a ~ 4-month period encompassing pre- and competitive seasons to evaluate within-week variations and differences between pre-season and competitive season. External load was assessed using inertial measurement units (IMU), while internal load was evaluated using session rating of perceived exertion (sRPE). Mixed model analyses were employed for statistical analysis. Results showed that load peaked on MD + 2 and MD≥-3, followed by a decline towards MD-1. Significant reductions (p < 0.05) were observed in total distance (mean±SE: 5129 ± 183 and 5390 ± 159 vs. 3171 ± 126 m, MD + 2, MD≥-3 vs. MD-1), accumulated acceleration load (610 ± 21 and 644 ± 18 vs. 407 ± 15 au), and acceleration distance high (679 ± 52 and 854 ± 45 vs. 294 ± 36 m) reflecting a structured tapering approach, whereas sRPE load was unchanged (350 ± 31 and 337 ± 26 vs. 273 ± 21 au, p > 0.05). Peak load was not observed at MD. Pre-season values were for most variables like early week training sessions indicating a focus on pre-season fitness improvements and maintenance in early-week sessions. This study showed how training load in professional highly trained team handball was distributed to stimulate maintenance of fitness while securing readiness for matches.

Assessment of phosphorus loading dynamics in a tropical reservoir with high seasonal water level changes

Objective: To determine differences in internal and external load during an unofficial match between First Division Adult and U-19 players of the same club using portable global positioning systems. Methods: During an unofficial match between an adult and a U-19 category, internal load through heart rate and external load through running performance were monitored. Seven adult players (25.57 ± 5.06 years) and five U-19 players (18.6 ± 0.54 years) were monitored. Comparisons were made between categories in the first half, second half and total match using the Mann-Whitney U test and calculating effect sizes through percent difference (PD). Results: Differences were found (p&lt;0.05) of external load in maximum speed in first half and total match, with U-19 players reaching the highest values (maximum speed first half: 32.34 vs 27.77 km/h and PD = 15.3%; total match: 32.6 vs 28.14 km/h and PD = 14.7%). On the other hand, differences in internal load were only found in heart rate zone 3 (70 to 80% of maximum HR) in the first and second half, where U-19 players spent more time in this zone (heart rate zone 3 first half: 6.1 vs 1.73 minutes and PD = 111.6%; second half: 20.49 vs 5.21 minutes and PD = 118.8%). No differences were found in the other variables analyzed. Conclusion: From the results obtained we can conclude that there are no differences in internal and external load in adult players with U-19 players, except for maximum speed and heart rate zone 3 in this team during a non-official match. Therefore, for practical purposes, the U-19 players of this team could be in conditions to face the physical demands required by the adult category competition.

We quantified summer internal phosphorus (P) loads and all the major P fluxes in Lake Mendota, Wisconsin, a deep stratified eutrophic lake, during two summers of contrasting external loads to determine ( i) whether internal loading by entrainment (mixing at the thermocline) is a significant part of the epilimnetic P budget and ( ii) what factors lead to interannual variability in internal loading. We estimated variables for the P budget weekly (standing stock, sedimentation) or daily (outflow, inflow, and entrainment) during a summer of average runoff (1992) and one of higher than average runoff (1993). Entrainment, estimated by calculating the amount of P transported into the epilimnion after the thermocline deepened following storms, was about 10 times higher than external loading during 1992, but was about equal to external loading during 1993. When entrainment was included, the epilimnetic P budget balanced. Interannual variability in internal loading appears to be due to a combination of water column stability, weather, and the P levels accumulated in the metalimnion. External loads to the epilimnion during summer 1993 were much higher than in 1992 (7.0 and 0.9 mg P·m -2 ·day -1 , respectively); however, total loads (internal + external) were more similar (12.5 and 7.8 mg P·m -2 ·day -1 in 1993 and 1992, respectively). Although summer chlorophyll concentrations were similar in the two summers, blue-green algal biomass in 1993 was about double that in 1992.

Monitoring the training load is crucial in sports science research, as it provides scientific evidence for assessing training effects, optimizing athletic performance, and preventing overtraining by quantifying both external and internal loads. Although traditional monitoring methods have made significant progress, infrared thermography (IRT) technology, with its non-contact, real-time, and non-invasive characteristics, is gradually emerging as an effective tool for evaluating the relationship between the training load and physiological responses. This study evaluated 31 healthy male adults (age 21.9 ± 2.7 years, weight 75 ± 8.26 kg, and training duration 240 ± 65 min/week) performing incremental exhaustive exercise on a cycle ergometer (with a 60W starting load, increasing by 20W per minute). Entropy analysis was used to quantitatively assess the surface radiation patterns of regions of interest (forehead, chest, and abdomen) obtained through thermal imaging. Compared to baseline, significant differences in the surface radiation patterns of the regions of interest were observed at the point of exhaustion (p ≤ 0.01). Correlation analysis revealed strong associations between the external load, oxygen consumption, and chest temperature entropy (r = 0.973 and 0.980). Cluster analysis of the chest entropy, external load, and oxygen consumption showed a non-linear increasing trend in their inter-relationships. Further individual analysis demonstrated positive correlations between the percentage increase in the chest entropy and both the external load (r = 0.70-0.98) and oxygen consumption (r = 0.65-0.97). Entropy analysis offers a new approach for quantitatively assessing surface radiation patterns from infrared thermography, and reveals the coupling relationship between thermoregulation and metabolic responses during exercise.

The purpose of this study was to analyze the external and internal load of Costa Rican handball referees according to sex and game periods. Nine referees (6 men and 3 women) were monitored during U19 handball matches, using an ultra-wide band local positioning system (UWB) and WIMUPro™ inertial units (IMU). The results showed a total distance of 4566.54±494.02 m (46.95% at 0-6 km/h, 32.97% at 6-12 km/h, 18.11% at 12-18 km/h and 1.96% &gt;18 km/h). 1298.34±151.42 m/s2 accelerations and 1297.73±152.09 m/s2 decelerations were performed. Maximal speed was 19.63±1.85 km/h and average speed was 4.80±0.34 km/h. Player LoadRT was 50.53±9.39 UA. Maximal and average heart rate was 170.59±18.20 bpm 143.06±16.94 bpm respectively. 60% of the efforts were &lt;80% of maximum heart rate. Total energy expenditure was 372.34±67.80 kcal. No significant differences were found in physiological variables between sexes, although men covered greater distance at 0-6 km/h. In the second periods the total distance (m/min), distance at 6-12 km/h, 12-18 km/h (m/min) and &gt;18 km/h, average speed, impacts at 3-5g and &gt;5g, Player LoadRT, and energy expenditure decreased. In conclusion, sex does not seem to affect the external or internal load, while the game period influenced on the external load.

This preliminary study had two aims: (i) to compare the internal and external loads between training sessions and official games in youth basketball players; (ii) to investigate the effects of the playing role on physical capacities, basketball skills, and internal and external loads accumulated during training and competition. Thirteen under-16 male basketball players, aged 15.30 ± 0.88 years, were followed over 10 consecutive weeks and assigned into two groups according to their playing role: starters and rotation players. Prior to the 10-week monitoring period, players' training experience, basic anthropometrics, physical capacities, and basketball skills were assessed. Then, internal and external loads were monitored in formal training and official competition. Data were analyzed using non-parametric techniques. Players attained significantly higher values in most measures of internal and external loads during official games (r = 0.82 to 0.88, p < 0.01). Starters outperformed rotation players in the 20-m sprint (r = 0.61, p < 0.05), the lane agility drill (r = 0.77, p < 0.01), and the control dribble (r = 0.73, p < 0.01). They also reached a lower HRpeak in practice (r = 0.65, p < 0.05), but a higher %HRpeak (r = -0.61, p < 0.05) and greater scores in the summated-heart-rate-zones model (r = -0.61, p < 0.05) as well as the dynamic stress load during official games (r = -0.57, p < 0.05). The findings highlight that young basketball players apparently do not train as intensely as they play. Moreover, it was during competition that starting players experienced higher internal and external loads. It is recommended that basketball coaches regularly monitor loads in both formal training and competition to closely match game demands when planning their practices. Finally, it is suggested that future research includes larger sample sizes to provide a more comprehensive understanding of both internal and external loads in youth basketball.