Maximal Performance Research Articles

Abstract 13075: Hemodynamic Estimation of Personalized Initial Target Heart Rate in Patients With Atrial Fibrillation With Rapid Ventricular Response

Introduction: Rate control in atrial fibrillation (AF) has played a pivot role in clinical setting even though recent advances in rhythm control. There are few evidences for target heart rate in either acute or chronic situations. Hypothesis: This study tried to estimate personalized initial target heart rate based on hemodynamic assessment in patient with AF with rapid ventricular response. Methods: A total of 72 patients with AF were included. From the equation between preceding RR interval and left ventricular peak ejection velocity adjusted by pre-preceding RR interval, the relationship between cardiac performance representing cardiac output and heart rate was calculated, and heart rate showing maximal cardiac performance (HRmax) was obtained (Left Figure). Results: Mean HRmax was 126±21.8/min (from 75/min to 188/min). Three-fourth patients had HRmax >120/minute (Right Figure). The relationship between Vpe and preceding RR interval showed two types, biphasic or monophasic resulting in similar patterns between cardiac performance and heart rate (Left Figure). HRmax <100/min was found in 7 patients in whom left ventricular dilatation, dysfunction, and/or aortic regurgitation were observed (Left Figure C). Lower HRmax was independently associated with larger aorta size (r=0.48, p<0.001), the absence of mitral regurgitation (r=0.43, p<0.005), prescription of angiotensin converting enzyme inhibitor or angiotensin receptor blocker (r=0.39, p=0.001), and a history of heart failure (r=0.21, p=0.019). Conclusions: In most AF patients, hemodynamic approach suggested that tachycardia of 120/min or more is tolerable. The method of this study may be useful to deliver individually designed management by identifying patient that strict rate control is mandatory. In other patients, management of underlying causes for tachycardia is enough without medications for mechanical heart rate control to avoid adverse effects without clinical benefits.

Thirty Years of Psychological Wisdom Research: What We Know About the Correlates of an Ancient Concept

Psychologists have studied the ancient concept of wisdom for 3 decades. Nevertheless, apparent discrepancies in theories and empirical findings have left the nomological network of the construct unclear. Using multilevel meta-analyses, we summarized wisdom’s correlations with age, intelligence, the Big Five personality traits, narcissism, self-esteem, social desirability, and well-being. We furthermore examined whether these correlations were moderated by the general approach to conceptualizing and measuring wisdom (i.e., phenomenological wisdom as indexed by self-report vs. performative wisdom as indexed by performance ratings), by specific wisdom measures, and by variable-specific factors (e.g., age range, type of intelligence measures, and well-being type). Although phenomenological and performative approaches to conceptualizing and measuring wisdom had some unique correlates, both were correlated with openness, hedonic well-being, and eudaimonic well-being, especially the growth aspect of eudaimonic well-being. Differences between phenomenological and performative wisdom are discussed in terms of the differences between typical and maximal performance, self-ratings and observer ratings, and global and state wisdom. This article will help move the scientific study of wisdom forward by elucidating reliable wisdom correlates and by offering concrete suggestions for future empirical research based on the meta-analytic findings.

Field-Derived Maximal Power Output in Cycling: An Accurate Indicator of Maximal Performance Capacity?

To determine the validity of field-derived mean maximum power (MMP) values for monitoring maximal cycling endurance performance. Twenty-seven male professional cyclists performed 3 timed trials (TTs) of 1-, 5-, and 20-minute duration that were used as the gold standard reference. Field-based power output data (3336 files; 124 [25] per cyclist) were registered during the preparatory (60d pre-TT, including training data only) and specific period of the season (60d post-TT, including both training and competitions). Comparisons were made between TT performance (mean power output) and MMP values obtained for efforts of the same duration as TT (MMP of 1-, 5-, and 20-min duration). The authors also compared TT- and MMP-derived values of critical power (CP) and anaerobic work capacity. A large correlation (P < .001, r > .65) was found between MMP and TT performance regardless of the effort duration or season period. However, considerable differences (P < .05, standard error of measurement [SEM] > 5%) were found between MMP and TT values for all effort durations in the preparatory period, as well as for the derived CP and anaerobic work capacity. Significant differences were also found between MMP and TT of 1 minute in the specific period, as well as for anaerobic work capacity, yet with no differences for MMP of 5- and 20-minute duration or the derived CP (P > .05, SEM < 5%). MMP values (for efforts ≥5min) and the associated CP obtained from both training sessions and competitions can be considered overall accurate indicators of the cyclist's maximal capabilities, but specific tests might be necessary for shorter efforts or when considering training sessions only.

Joint User Association and Hybrid Beamforming Designs for Cell-Free mmWave MIMO Communications

Cell-free millimeter-wave (mmWave) multiple-input multiple-output (MIMO) communications have been proposed as promising enablers for the next generation wireless networks. In this paper, we study the user association and hybrid beamforming in cell-free mmWave systems without full channel state information (CSI) acquisition. We consider a cloud radio access network (C-RAN), where multiple remote radio heads (RRHs) are distributed to communicate with users via analog beamforming, and connected to a centralized baseband unit (BBU) through fronthaul links which executes digital beamforming. We aim to jointly design user association, hybrid beamforming, and fronthaul compression with the aid of uplink training. A train-and-design framework is developed to achieve this goal. In particular, we first propose a two-stage uplink training approach to assist RRH-level design, during which the analog beamforming and user association are obtained. After that, digital beamforming and fronthaul compression are optimized at BBU based on the training results. Two performance metrics are considered in this paper, i.e. weighted sum-rate maximization and max-min fairness. Simulation results demonstrate the effectiveness of the proposed train-and-design framework for both sum-rate maximization and max-min fairness performance metrics. It is shown that the proposed algorithms can achieve comparable performance to the full-digital beamformer.

A Comparison of Warm-Up Effects on Maximal Aerobic Exercise Performance in Children.

The aim of this study was to compare the warm-up effects of treadmill walking (TW) with a dynamic (DY) bodyweight warm-up on maximal aerobic exercise performance in children. Sixteen children (10.9 ± 1.5 vrs) were tested for peak oxygen uptake (VO2 peak) on 2 nonconsecutive days following different 6 min warm-up protocols. TW consisted of walking on a motor-driven treadmill at 2.2 mph and 0% grade whereas the DY warm-up consisted of 9 body weight movements including dynamic stretches, lunges, and jumps. Maximal heart rate was significantly higher following DY than TW (193.9 ± 6.2 vs. 191.6 ± 6.1 bpm, respectively; p = 0.008). VO2 peak (54.8 ± 9.6 vs. 51.8 ± 8.7 mL/kg/min; p = 0.09), maximal minute ventilation (68.9 ± 14.8 vs. 64.9 ± 9.4 L/min; p = 0.27), maximal respiratory exchange ratio (1.12 ± 0.1 vs. 1.11 ± 0.1; p = 0.85) and total exercise time (614.0 ± 77.1 vs. 605 ± 95.0 s; p = 0.55) did not differ significantly between DY and TM warm-ups, respectively. These findings indicate that the design of the warm-up protocol can influence the heart rate response to maximal aerobic exercise and has a tendency to influence VO2 peak. A DY warm-up could be a viable alternative to a TW warm-up prior to maximal exercise testing in children.

Interindividual variability of adaptations following either traditional strength or power training combined to endurance training in older men: A secondary analysis of a randomized clinical trial

This study aimed to investigate the interindividual responses following two different concurrent training (CT) regimens in neuromuscular, cardiorespiratory and functional outcomes of older men. Thirty-five older men (65.8 ± 3.9 years) were randomly allocated into one of two CT groups: power training (PT) + high-intensity interval training (HIIT) (n = 17); or traditional strength training (TST) + HIIT (n = 18). Maximal dynamic strength (one-repetition maximum, 1RM), rate of force development at 100 milliseconds (RDF100), countermovement jump power (CMJ), quadriceps femoris muscle thickness (QF MT), functional tests (sit-to-stand, timed-up-and-go, and stair climbing), and peak oxygen consumption (VO2peak) were assessed pre-, post-8 and post-16 weeks of training. The Chi-squared test was used for assessing differences in the prevalence of responders (Rs), non-responders (NRs), and adverse responders (ARs). Similar prevalence of individual responses (Rs, NRs and ARs) between groups were observed after intervention in almost all outcomes: 1RM; power at CMJ; QF MT, and functional tests (P > 0.05). However, a significant difference in the distribution of Rs, NRs and ARs between groups was observed in the RFD100 after 16 weeks (p = 0.003), with PT + HIIT group presenting high prevalence of Rs than TST + HIIT (100 % vs. 50 %). The inclusion of explosive-type of contractions in a concurrent training regime induces greater responsiveness in the RFD100 in older men, while no differences compared to traditional strength training are observed in maximal strength, muscle size, VO2peak, and functional performance.

Effect of different training frequencies on maximal strength performance and muscle hypertrophy in trained individuals-a within-subject design.

Several studies comparing resistance training (RT) frequencies may have been affected by the large between-subject variability. This study aimed to compare the changes in lower limbs maximal dynamic strength (1RM) and quadriceps femoris cross-sectional area (CSA) after a RT with different weekly frequencies in strength-trained individuals using a within-subject design. Twenty-four men participated in a 9-week RT program, being randomly divided into two conditions: resistance training with equalized total training volume (RTEV) and with unequalized total training volume (RTUV). The RT protocol used the unilateral leg press 45° exercise and each subject’s lower limb executed one of the proposed frequencies (one and three times/week). All conditions effectively increased 1RM and CSA (p<0.001); however, no significant differences were observed in the values of 1RM (p = 0.454) and CSA (p = 0.310) between the RT frequencies in the RTEV and RTUV conditions. Therefore, RT performed three times a week showed similar increases in 1RM and CSA to the program performed once a week, regardless of training volume equalization. Nevertheless, when the higher RT frequency allowed the application of a greater TTV (i.e., RTUV), higher effect size (ES) values (0.51 and 0.63, 1RM and CSA, respectively) were observed for the adaptations.

A Widespread Assessment and Open Issues on Image Captioning Models

Automated generation of image captions is a demanding AI crisis as it necessitates the exploitation of numerous methods from diverse computer science fields. Deep learning (DL) approaches have revealed marvelous results in a lot of diverse appliances. On the other hand, data augmentation in DL that imitates the quantity and the variety of training data without the need of gathering additional data is a hopeful area in machine learning (ML). Producing textual descriptions for a specified image is a demanding task using the computer. This survey makes a critical analysis of about 65 papers regarding image captioning. More particularly, varied performance measures that are contributed in diverse articles are analyzed. In addition, a comprehensive study is made regarding the maximal performances and varied features deployed in each work. Moreover, chronological analysis and dataset analysis are done and finally, the survey extends with the determination of varied research challenges, which might be productive for the analysts to endorse enhanced upcoming works on image captioning.

Impairment in maximal lactate steady state after carbon monoxide inhalation is related to training status.

What is the central question of this study? What is the effect of an elevated carboxyhaemoglobin (COHb) concentration following carbon monoxide inhalation on the maximal lactate steady state (MLSS) in humans and is this effect dependent on aerobic fitness? What is the main finding and its importance? An elevated COHb concentration intensified physiological responses to exercise at the MLSS - including heart rate, ventilation and peripheral fatigue - in general and reduced the MLSS (i.e., destabilized the blood lactate concentration) in trained but not untrained males and females. This study investigated whether a lower effective [Hb], induced by carbon monoxide (CO) inhalation, reduces the peak oxygen uptake ( ) and the maximal lactate steady state (MLSS) and whether training status explains individual variation in these impairments. Healthy young participants completed two ramp incremental tests (n=20, 10 female) and two trials at MLSS (n=16, eight female) following CO rebreathe tests and sham procedures (SHAM) in random orders. All fitness variables were normalized to fat-free mass (FFM) to account for sex-related differences in body composition, and males and females were matched for aerobic fitness. The (mean (SD): -4.2 (3.7)%), peak power output (PPO) (-3.3 (2.2)%) and respiratory compensation point (RCP) (-6.3 (4.5)%) were reduced in CO compared with SHAM (P<0.001 for all), but the gas exchange threshold (-3.3 (7.1)%) was not (P=0.077). Decreases in (r =-0.45; P=0.047) and PPO (r=-0.49; P=0.029) in CO were correlated with baseline aerobic fitness. Compared to SHAM, physiological and perceptual indicators of exercise-related stress were exacerbated by CO while cycling at MLSS. Notably, the mean blood lactate concentration ([La]) increased (i.e., Δ[La]>1.0mM) between 10min (5.5 (1.4) mM) and 30min (6.8 (1.3) mM; P=0.026) in CO, with 9/16 participants classified as unstable. These unstable participants had a higher (66.2 (8.5) vs. 56.4 (8.8) mlkg FFM-1 min-1 , P=0.042) and at MLSS (55.8 (7.0) vs. 44.3 (7.0) mlkg FFM-1 min-1 , P=0.006) compared to the stable group. In conclusion, a reduced O2 -carrying capacity decreased maximal and submaximal exercise performance, with higher aerobic fitness associated with greater impairments in both.

Upper Body Muscle Activation And Measures Of Sprint Performance

PURPOSE: Effective arm swing and core muscle activation are involved in acceleration and maximal sprinting, yet muscle activity in these areas have not been measured via electromyography (EMG) during over ground sprinting trials. The purpose of this study was to explore the relationship between muscle activation of the upper body and measures of performance during sprint acceleration and maximal sprinting. METHODS: Sixteen participants (20.93 ± 0.96 yrs.; 1.71 ± 0.07 m; 67.69 ± 11.81 kg) completed six 40-m sprint trials on an outdoor track, with three from a block start and three from a split start. Muscle activation was measured via EMG in the triceps brachii, biceps brachii, upper trapezius, anterior deltoid, latissimus dorsi, erector spinae, rectus abdominis, and oblique muscles, recorded as a percentage of maximal voluntary isometric contraction. Split times recorded during each sprint were used to calculate acceleration, net horizontal force (Fh), and the ratio of Fh and resultant ground reaction force (%RF) using previously validated methods. Repeated measures multilevel modeling was used to evaluate the relationship between mean upper body muscle activation and average acceleration, Fh, and %RF during each 10-m window of the sprint. RESULTS: During the 0-10 m window, mean activation of the upper trapezius showed a significant positive relationship with acceleration (t = 2.66, p = 0.01), Fh (t = 2.20, p = 0.03), and %RF (t = 2.57, p = 0.01), erector spinae activation was positively associated with %RF (t = 2.42, p = 0.02), and biceps activation was negatively associated with Fh (t = -2.23, p = 0.03). In the 30-40 m window, there was a significant negative relationship between mean latissimus dorsi activation and %RF (t = -2.16, p = 0.04). There were no significant relationships between upper body muscle activation and indicators of sprint performance detected during the 10-20 m or 20-30 m windows. CONCLUSIONS: These results indicate that upper trapezius muscle activity is important during initial sprint acceleration, which agrees with past research on scapular restriction limiting maximal acceleration while sprinting. After the initial period of sprint acceleration, there was no evidence that greater activation of certain upper body muscles was related to improving maximal sprinting performance.

Evaluation Of Valid VO2max Criteria For Graded Exercise Testing In Cancer Survivors

INTRO: Using a metabolic cart (met cart) to obtain an individual's maximal oxygen consumption (VO2max) is considered the gold standard method of measurement. An accurate VO2max value is important in every population for individualized exercise prescriptions (ExRx), but specifically within the cancer population due to treatment status. Certain criteria must be met for a value to be considered a true VO2max. Utilizing gas analysis to track the changing respiratory exchange ratio (RER) and achieving >1.10 is the best criteria to determine if true max was obtained. Other maximal criteria such as 85% of heart rate max (HR) using the Tanaka formula and rate of perceived exertion (RPE) of >7 on the Modified Borg Scale also have the potential to be used as maximal criteria eliminating the need for a met cart. It is unknown if HR and RPE can be used independently as valid termination criteria in the cancer population during VO2max assessments. PURPOSE: To evaluate the frequency of achieving VO2max as determined by RER and alternate maximal criteria using HR and RER in a sample of cancer survivors. METHODS: Forty cancer survivors participated in the study. Subjects performed one GXT per week for three weeks using gas analysis. RER, HR, and RPE values were recorded. A total of 111 GXTs were used for data analysis. A Cochran’s Q test was used to determine if there were differences in the frequency of successful achievement of RER, HR, and RPE maximal criteria during the GXTs. RESULTS: Maximal criteria was successfully met in 95, 89, and 102 GXTs when evaluating RER, HR, and RPE, respectively. No significant differences occurred in the achievement of max between RER, HR, and RPE criteria (p < 0.061). CONCLUSION: The findings from this data set suggest that HR and RPE may be valid and suitable criteria for termination of a GXT if obtaining an RER value is not feasible or clinically practical. Cancer survivors experience toxicities such as skin irritation, muscular impairments, balance issues, peripheral neuropathy, and/or cancer related fatigue, making use of a met cart and mask potential impediments to maximal performance. Elimination of the met cart may allow the individual to advance further into a GXT leading to more accurate VO2max values and thus more accurate ExRx in the cancer population.

Effects of High and Low Training Volume with the Nordic Hamstring Exercise on Hamstring Strength, Jump Height, and Sprint Performance in Female Football Players: A Randomised Trial.

The evidence-based hamstring strengthening programme for prevention of hamstring injuries is not adopted by football teams because of its high training volume. This study on female football players investigated if high-volume training with the Nordic hamstring exercise is more effective on hamstring strength, jump height, and sprint performance than low-volume training. We also examined the time course of changes in muscle strength during the intervention period. Forty-five female football players were randomised to a high- (21 sessions, 538 total reps) or low-volume group (10 sessions, 144 total reps) and performed an 8-week training intervention with the Nordic hamstring exercise during the preseason. We tested hamstring strength (maximal eccentric force with NordBord and maximal eccentric torque with isokinetic dynamometer), jump height, and 40 m sprint before and after the intervention. The NordBord test was also performed during training weeks 4 and 6. Both groups increased maximal eccentric force (high-volume: 29 N (10%), 95% CI: 19-38 N, p < 0.001, low-volume: 37 N (13%), 95% CI: 18-55 N, p = 0.001), but there were no between-group differences (p = 0.38). Maximal eccentric torque, jump height, and sprint performance did not change. Maximal eccentric force increased from the pretest to week 6 (20 N (7%), 95% CI: 8 to 31 N, p < 0.001), but not week 4 (8 N (3%), 95% CI: -2 to 18 N, p = 0.22). High training volume with the Nordic hamstrings exercise did not lead to greater adaptations in strength, jump height, or speed than a low-volume programme. Players in both groups had to train for at least 6 weeks to improve maximal eccentric force significantly.

Acute effect of auxotonic and isometric contraction evaluated by infrared thermography in handball players

The Infrared Thermography (IRT) is being used in the field of sport as a means of quantifying the effects of workload. The aims of this study were (i) to determine the variations in skin temperature (Tsk) of the lower limbs after an effort of auxotonic and isometric squat contractions using infrared thermography and (ii) to study jumping performance variations in handball players after those two different contraction types. A total of 15 national level handball players voluntarily participated in the study (age: 23.20 ± 5.23 years). Two types of protocols – isometric and auxotonic – were performed on different days, having previously calculated the maximal isometric squat strength and auxotonic 1RM. During the data collection, participants performed a specific standardized warm-up and then randomly performed 4x10 repetitions of auxotonic squat to 90° of knee flexion at 70% of 1RM and 4x10 s of isometric squat effort at 90° of knee flexion, at 70% of maximal isometric squat strength (both with a passive recovery of 90 s seated). Rate of perceived exertion (RPE) and countermovement jumping performance (CMJ) were measured before and immediately after efforts. Additionally, infrared thermography data from twelve regions of interest of the lower limbs were registered before, immediately after and 15 min after finishing the effort. The main results indicated no significant differences for RPE (p = 0.486), CMJ vertical height (VH; p = 0.344) and Tsk (p > 0.05) in any of the regions of interest after protocols. Significant differences (p < 0.05) were found for the time of data collection on Tsk with similar pre- and post-15 min values. In conclusion, Tsk decreased after both isometric and auxotonic effort at 70% of the maximal performance and recovered baseline values within 15 min of completion. Both efforts produced similar effects on skin temperature and did not affect jumping performance after exercise.

The thermal performance curve for aerobic metabolism of a flying endotherm.

Performance benefits of stable, warm muscles are believed to be important for the evolution of endothermy in mammals, birds and flying insects. However, thermal performance curves have never been measured for a free-flying endotherm, as it is challenging to vary body temperatures of these animals, and maximal flight performance is difficult to elicit. We varied air temperatures and gas densities to manipulate thoracic temperatures of flying honeybees from 29°C to 44°C, with low air densities used to increase flight metabolic rates to maximal values. Honeybees showed a clear thermal performance curve with an optimal temperature of 39°C. Maximal flight metabolic rates increased by approximately 2% per 1°C increase in thoracic temperature at suboptimal thoracic temperatures, but decreased approximately 5% per 1°C increase as the bees continued to heat up. This study provides the first quantification of the maximal metabolic performance benefit of thermoregulation in an endotherm. These data directly support aerobic capacity models for benefits of thermoregulation in honeybees, and suggest that improved aerobic capacity probably contributes to the multiple origins of endothermic heterothermy in bees and other insects.

Individualized Endurance Training Based on Recovery and Training Status in Recreational Runners.

ABSTRACTPurposeLong-term development of endurance performance requires a proper balance between strain and recovery. Because responses and adaptations to training are highly individual, this study examined whether individually adjusted endurance training based on recovery and training status would lead to greater adaptations compared with a predefined program.MethodsRecreational runners were divided into predefined (PD; n = 14) or individualized (IND; n = 16) training groups. In IND, the training load was decreased, maintained, or increased twice a week based on nocturnal heart rate variability, perceived recovery, and heart rate–running speed index. Both groups performed 3-wk preparatory, 6-wk volume, and 6-wk interval periods. Incremental treadmill tests and 10-km running tests were performed before the preparatory period (T0) and after the preparatory (T1), volume (T2), and interval (T3) periods. The magnitude of training adaptations was defined based on the coefficient of variation between T0 and T1 tests (high >2×, low <0.5×).ResultsBoth groups improved (P < 0.01) their maximal treadmill speed and 10-km time from T1 to T3. The change in the 10-km time was greater in IND compared with PD (−6.2% ± 2.8% vs −2.9% ± 2.4%, P = 0.002). In addition, IND had more high responders (50% vs 29%) and fewer low responders (0% vs 21%) compared with PD in the change of maximal treadmill speed and 10-km performance (81% vs 23% and 13% vs 23%), respectively.ConclusionsPD and IND induced positive training adaptations, but the individualized training seemed more beneficial in endurance performance. Moreover, IND increased the likelihood of high response and decreased the occurrence of low response to endurance training.

Effects of standardized ileal digestible lysine level on growth performance and economic return for 18 to 128 kg Duroc-sired pigs.

The recent shift of the U.S. swine industry toward improved pork quality, such as color, marbling, and firmness, has led to increased use of Duroc-sired pigs in the marketplace. Our objective was to determine the standardized ileal digestible (SID) Lys requirement estimates for Duroc-sired (600 × 241, DNA, Columbus, NE) pigs from 18 to 128 kg BW. We conducted a series of experiments using corn-soybean meal-based diets with pigs allotted to 6 or 7 treatments in randomized complete block designs. In all experiments an equal number of barrows and gilts were used within a pen. In experiment 1, 300 pigs (initially 18.4 ± 0.50 kg) were used with 5 pigs per pen and 10 pens per treatment with 6 SID Lys levels from 1.00% to 1.50%. Increasing SID Lys increased (linear, P < 0.040) final BW, ADG, G:F, and Lys intake/kg of gain, and decreased (linear, P = 0.012) ADFI. In experiment 2, 608 pigs (initially 36.3 ± 0.91 kg) were used with 7 to 9 pigs per pen and 12 pens per treatment with 6 SID Lys levels from 0.80% to 1.20%. Increasing SID Lys increased (linear, P ≤ 0.036) ADG, G:F, and Lys intake/kg of gain. In experiment 3, 700 pigs (initially 53.2 ± 0.86 kg) were used with 8 to 10 pigs per pen and 12 pens per treatment with 6 SID Lys levels from 0.65% to 1.00%. Increasing SID Lys increased (linear, P < 0.001) final BW, ADG, and Lys intake/kg of gain, decreased (quadratic, P = 0.004) ADFI, and improved (quadratic, P < 0.001) G:F. In experiment 4, 616 pigs (initially 76.4 ± 1.25 kg) were used with 8 to 10 pigs per pen and 5, 6, or 11 pens per treatment with 7 SID Lys levels from 0.58% to 1.00%. Increasing SID Lys increased (linear, P ≤ 0.022) ADG, Lys intake per kilogram of gain, and G:F. In experiment 5, 679 pigs (initially 103.8 ± 1.32 kg) were used with 8 to 10 pigs per pen and 11 or 12 pens per treatment with 6 SID Lys levels from 0.43% to 0.78%. Increasing SID Lys increased (linear, P ≤ 0.043) final BW, ADG, and Lys intake per kilogram of gain, and improved (quadratic, P ≤ 0.032) G:F. Using results from all experiments, the quadratic equation of Lys:calorie ratio, g of SID Lys/Mcal of NE = 0.0002611 × BW2 - 0.0711037 × BW + 7.284 was developed to reflect the requirement for maximal growth performance from 18 to 128 kg BW. Maximal income over feed cost (IOFC) is best described by the quadratic equation: Lys:calorie ratio, g of SID Lys/Mcal of NE = 0.0001558 × BW2 - 0.04030769 × BW + 5.410. These data provide updated SID Lys estimates for Duroc-sired grow-finish pigs.

White Paper: An Integrated Perspective on the Causes of Hypometric Metabolic Scaling in Animals.

Larger animals studied during ontogeny, across populations, or across species, usually have lower mass-specific metabolic rates than smaller animals (hypometric scaling). This pattern is usually observed regardless of physiological state (e.g. basal, resting, field, maximally-active). The scaling of metabolism is usually highly correlated with the scaling of many life history traits, behaviors, physiological variables, and cellular/molecular properties, making determination of the causation of this pattern challenging. For across-species comparisons of resting and locomoting animals (but less so for across populations or during ontogeny), the mechanisms at the physiological and cellular level are becoming clear. Lower mass-specific metabolic rates of larger species at rest are due to a) lower contents of expensive tissues (brains, liver, kidneys), and b) slower ion leak across membranes at least partially due to membrane composition, with lower ion pump ATPase activities. Lower mass-specific costs of larger species during locomotion are due to lower costs for lower-frequency muscle activity, with slower myosin and Ca++ ATPase activities, and likely more elastic energy storage. The evolutionary explanation(s) for hypometric scaling remain(s) highly controversial. One subset of evolutionary hypotheses relies on constraints on larger animals due to changes in geometry with size; for example, lower surface-to-volume ratios of exchange surfaces may constrain nutrient or heat exchange, or lower cross-sectional areas of muscles and tendons relative to body mass ratios would make larger animals more fragile without compensation. Another subset of hypotheses suggests that hypometric scaling arises from biotic interactions and correlated selection, with larger animals experiencing less selection for mass-specific growth or neurolocomotor performance. A additional third type of explanation comes from population genetics. Larger animals with their lower effective population sizes and subsequent less effective selection relative to drift may have more deleterious mutations, reducing maximal performance and metabolic rates. Resolving the evolutionary explanation for the hypometric scaling of metabolism and associated variables is a major challenge for organismal and evolutionary biology. To aid progress, we identify some variation in terminology use that has impeded cross-field conversations on scaling. We also suggest that promising directions for the field to move forward include: 1) studies examining the linkages between ontogenetic, population-level, and cross-species allometries, 2) studies linking scaling to ecological or phylogenetic context, 3) studies that consider multiple, possibly interacting hypotheses, and 4) obtaining better field data for metabolic rates and the life history correlates of metabolic rate such as lifespan, growth rate and reproduction.

High-Intensity Interval Training with Cycling and Calisthenics: Effects on Aerobic Endurance, Critical Power, Sprint and Maximal Strength Performance in Sedentary Males

TABATA protocol is considered to be one of the most effective strategies among high-intensity interval training (HIIT) methods. A limited number of studies have compared the chronic effects of cycling-based and calistenic HIIT in TABATA-type. The aim of this study was to compare the chronic effects of a 8-week TABATA-type calisthenic high-intensity interval and high-intensity interval in cycling on aerobic endurance, sprint and maximal strength performance in sedentary men. 17 sedentary males participated in our study. Participants were randomly divided into calisthenic HIIT (n=9) and cycling HIIT (n=8) groups. Training groups were given 3-sessions of exercise per week on non-consecutive days for 8 weeks. Before and after the 8-week training, the body mass, body mass index, fat percentage, 30-m sprint, 1-repetition maximal strength, aerobic power and critical power levels of the participants were determined. No statistically significant different was observed in body mass (p=0.917), body mass index (p=0.928), and body fat ratio (p=0.980) in both training groups. However, both training groups achieved statistically significant improvements in peak power output (p=0.017), maximal oxygen consumption (p=0.040) and critical power (p=0.048), and there was no significant difference in the level of improvement between the groups (p&gt;0.05). There was no statistically significant difference in 1 repetition maximal strength and sprint values of both training groups (p&lt;0.05). TABATA type HIIT performed calistenic provides chronic effects similar to that of interval cycling form.

From performance curves to performance surfaces: Interactive effects of temperature and oxygen availability on aerobic and anaerobic performance in the common wall lizard

Abstract Accurately predicting the responses of organisms to novel or changing environments requires the development of ecologically‐appropriate experimental methodology and process‐based models. For ectotherms, thermal performance curves (TPCs) have provided a useful framework to describe how organismal performance is dependent on temperature. However, this approach often lacks a mechanistic underpinning, which limits our ability to use TPCs predictively. Furthermore, thermal dependence varies across traits, and performance is also limited by additional abiotic factors, such as oxygen availability. We test a central prediction of our recent Hierarchical Mechanisms of Thermal Limitation (HMTL) Hypothesis which proposes that natural hypoxia exposure will reduce maximal performance and cause the TPC for whole‐organism performance to become more symmetrical. We quantified TPCs for two traits often used as fitness proxies, sprint speed and aerobic scope, in lizards under conditions of normoxia and high‐elevation hypoxia. In line with the predictions of HMTL, anaerobically fuelled sprint speed was unaffected by acute hypoxia while the TPC for aerobic scope became shorter and more symmetrical. This change in TPC shape resulted from both the maximum aerobic scope and the optimal temperature for aerobic scope being reduced in hypoxia as predicted. Following these results, we present a mathematical framework, which we call Temperature–Oxygen Performance Surfaces, to quantify the interactive effects of temperature and oxygen on whole‐organism performance in line with the HMTL hypothesis. This framework is transferrable across traits and levels of organization to allow predictions for how ectotherms will respond to novel combinations of temperature and other abiotic factors, providing a useful tool in a time of rapidly changing environmental conditions. Read the free Plain Language Summary for this article on the Journal blog.

Real intensity of physical activity capacity of patients with chronic disease: a cross-sectional study

The aim of this study was to evaluate the real intensity level of exercise in a sample of patients with chronic disease from obesity, rheumatology, hematology and other departments involved in a hospital-based program of adapted physical activity (APA). For this cross-sectional study, we studied seventy-five patients with chronic disease and no beta-blocker treatment. They systematically performed a cardiopulmonary exercise test before participating in a supervised APA practice using a telemetry wireless system to monitor heart rate (HR) during the first session. Based upon the results of the functional evaluation of exercise performance, we studied two groups of patients: (1) No limitation in exercise performance (maximal oxygen uptake greater than or equal to 80% of the theoretical reference) and (2) limited exercise performance (maximal oxygen uptake less than 80% of the theoretical value). Fifty-two patients (69.3%) were women, mean age was 42.6 (± 13.8), and mean BMI was 36.7 (± 10.6). Most patients had been referred for obesity (57.3%). We found 39 patients with normal exercise capacities and 36 patients with limited exercise performance. There were no significant differences in demographic and clinical characteristics between the two groups. For all populations, the mean and median real intensity levels of exercise in a sample of patients were moderate (55–70% HR max) and were the same for both groups. During the most intensive 15-min bout of the APA session, the HR for patients in both groups was greater than 70% of the actual maximum HR. This study observed a moderate level of APA exercise intensity in patients suffering from various chronic diseases. We found no significant difference in intensity level of exercise between patients’ capacities, i.e., with and without limitation of their maximal performance.