Are Machine Learning Models Used to Represent Accelerometry Data Robust to Age Differences?

Regular and sufficient amounts of physical activity (PA) are significant in increasing health benefits and mitigating health risks. Given the growing popularity of wrist-worn devices across all age groups, a rigorous evaluation for recognizing hallmark measures of physical activities and estimating energy expenditure is needed to compare their accuracy across the lifespan. The goal of the study was to build machine learning models to recognizing the hallmark measures of PA and estimating energy expenditure (EE), and to test the hypothesis that model performance varies across age-group: young [20-50 years], middle (50-70 years], and old (70-89 years]. Participants (n = 253, 62% women, aged 20-89 years old) performed a battery of 33 daily activities in a standardized laboratory setting while wearing a portable metabolic unit to measure EE that was used to gauge metabolic intensity. Participants also wore a Tri-axial accelerometer on the right wrist. Results from random forests algorithm were quite accurate at recognizing PA type; the F1-Score range across age groups was: sedentary [0.955 – 0.973], locomotion [0.942 – 0.964], and lifestyle [0.913 – 0.949]. Recognizing PA intensity resulted in lower performance; the F1-Score range across age groups was: sedentary [0.919 – 0.947], light [0.813 – 0.828], and moderate [0.846–0.875]. The root mean square error range was [0.835–1.009] for the estimation of EE. The F1-Score range for recognizing individual PAs was [0.263–0.784]. In conclusion, machine learning models used to represent accelerometry data are robust to age differences and a generalizable approach might be sufficient to utilize in accelerometer-based wearables.

The rationed feeding system of highly productive cows, taking into account their biochemical status

Researchers of the Department of Feed and Feeding of farm animals of the Federal State Budgetary Institution of Science “Vologda Scientific Center of the Russian Academy of Sciences”, as a result of research had been developed a draft system of rationed feeding system of highly productive cows, taking into account the biochemical status of the animal under different conditions of housing in the North of the European part of Russia, within the framework of the research topic AAAAA-A17-117032210064-7. A distinctive feature of the system is the physiological justification of the normative indicators of nutrient requirements for highly productive cows in the phases of lactation, depending on the level of daily productivity. The value of the development lies in a systematic approach to the requirements of complite rationed feeding of highly productive cows, feed quality, feeding regime and technique, taking into account the biochemical status of animals with different methods of housing. The feeding system provides for the year-round use of a feed mixture, which favorably affects the main indicators of the usefulness of the ration and, first of all, the concentration of energy (over 10,5 MJ/kg in dry matter), crude protein (at least 15,0 % in dry matter). The quality of raw protein characterizes the positive balance of protein not cleaved in the rumen. The practical application of the proposed rations with less than 50 % concentrated feed in their structure, the use of highly nutritious feed in the developed feeding scheme should be combined with regular monitoring of the biochemical status of the animal. Ensuring daily metabolism is based on the control of the main indicators of metabolic intensity, such as glucose, non-esterified fatty acids (not lower than 0,3 mg-eq/ml), alanine aminotransferase (not higher than 16 units/ml·h), aspartate aminotransferase (not higher than 27 units/ml·h), etc. The use of the feeding system ensures the productivity of animals at the level of 9000 kg of milk and above per lactation.

Enhanced Endogenous Amino Acids and Energy Metabolism Level for cAMP Biosynthesis by Arthrobacter sp. CCTCC 2013431 with Citrate as Cosubstrate

Objectives In our previous study, citrate was used as auxiliary energy substance for improving cAMP fermentation performance, however, the regulation mechanism of citrate on improved cAMP contents was not clear. To elucidate the regulation mechanism, cAMP fermentations with/without citrate addition were conducted in a 7 L fermentor using Arthrobacter sp. CCTCC 2013431 and assays on key enzymes activities, energy metabolism level, amino acids contents and peroxidation level were performed. Results With 3 g/L-broth sodium citrate added, cAMP concentration and conversion yield from glucose reached 4.34 g/L and 0.076 g/g which were improved by 30.7% and 29.8%, respectively, when compared with those of control. Citrate changed carbon flux distribution among different routes and more carbon flux was directed into pentose phosphate pathway beneficial to cAMP synthesis. Meanwhile, energy metabolism together with precursor amino acids levels were improved significantly owing to strengthened metabolic intensity of tricarboxylate cycle by exogenous citrate utilization which provided energy and substance basis for cAMP production. Moreover, higher glutamate synthesis and oxidative stress caused by citrate addition consumed excessive NADPH derived from pentose phosphate pathway by which feedback suppression for pentose phosphate pathway was relieved efficiently.Conclusion Citrate promoted cAMP fermentation production by Arthrobacter sp. CCTCC2013431 due to enhanced precursor amino acids, energy metabolism level and relieved feedback suppression for pentose phosphate pathway.

Cerebral blood flow rates in recent great apes are greater than in Australopithecus species that had equal or larger brains

Brain metabolic rate (MR) is linked mainly to the cost of synaptic activity, so may be a better correlate of cognitive ability than brain size alone. Among primates, the sizes of arterial foramina in recent and fossil skulls can be used to evaluate brain blood flow rate, which is proportional to brain MR. We use this approach to calculate flow rate in the internal carotid arteries ( Q ˙ ICA ) , which supply most of the primate cerebrum. Q ˙ ICA is up to two times higher in recent gorillas, chimpanzees and orangutans compared with 3-million-year-old australopithecine human relatives, which had equal or larger brains. The scaling relationships between Q ˙ ICA and brain volume ( V br ) show exponents of 1.03 across 44 species of living haplorhine primates and 1.41 across 12 species of fossil hominins. Thus, the evolutionary trajectory for brain perfusion is much steeper among ancestral hominins than would be predicted from living primates. Between 4.4-million-year-old Ardipithecus and Homo sapiens , V br increased 4.7-fold, but Q ˙ ICA increased 9.3-fold, indicating an approximate doubling of metabolic intensity of brain tissue. By contrast, Q ˙ ICA is proportional to V br among haplorhine primates, suggesting a constant volume-specific brain MR.

Using Music-Based Cadence Entrainment to Manipulate Walking Intensity

Background: While previous studies indicate an auditory metronome can entrain cadence (in steps per minute), music may also evoke prescribed cadences and metabolic intensities. Purpose: To determine how modulating the tempo of a single commercial song influences adults’ ability to entrain foot strikes while walking and how this entrainment affects metabolic intensity. Methods: Twenty healthy adults (10 men and 10 women; mean [SD]: age 23.7 [2.7] y, height 172.8 [9.0] cm, mass 71.5 [16.2] kg) walked overground on a large circular pathway for six 5-min conditions; 3 self-selected speeds (slow, normal, and fast); and 3 trials listening to a song with its tempo modulated to 80, 100, and 125 beats per minute. During music trials, participants were instructed to synchronize their step timing with the music tempo. Cadence was measured via direct observation, and metabolic intensity (metabolic equivalents) was assessed using indirect calorimetry. Results: Participants entrained their cadences to the music tempos (mean absolute percentage error = 5.3% [5.8%]). Entraining to a music tempo of 100 beats per minute yielded ≥3 metabolic equivalents in 90% of participants. Trials with music entrainment exhibited greater metabolic intensity compared with self-paced trials (repeated-measures analysis of variance, F1,19 = 8.05, P = .01). Conclusion: This study demonstrates the potential for using music to evoke predictable metabolic intensities.

WRIST-WORN TRI-AXIAL ACCELEROMETER VALIDATION IN YOUNG, MIDDLE-AGED, AND OLDER ADULTS

Purpose: This study evaluated wrist-worn accelerometers for estimating metabolic intensity and classifying activity types across a wide age spectrum. Methods: Participants (n=141, 67% women, aged 20-89 yrs) performed a battery of 31 common daily activities (e.g. washing dishes, walking) in a standardized laboratory setting. A tri-axial accelerometer was worn on the right wrist during each activity whiel a portable metabolic unit was used to measure oxygen consumption (ml/kg/min), which was converted into metabolic equivalents (METs). Random forest analyses estimated metabolic intensity and classified activity type based on seven data features. Resulting estimates were cross-evaluated on a separate sample of 16 participants who performed a sub-set of activities in their home. Results: In the laboratory setting, mean differences between measured and predicted MET value for sedentary (0.36), lifestyle (0.02) and locomotor (0.30) activities were low, but the 95% limits of agreement ranges were relatively large (+/-1.0, +/-1.8, +/-3.1, respectively). Data features were 85%, 88%, and 71% accurate for identifying sedentary, lifestyle and locomotor activities. Prediction equations had an overall mean difference of 0.19 METs (95% limits of agreement = -1.3 to 1.7) when activities were performed at home. Conclusion: Data features extracted from a wrist worn tri-axial accelerometer provide a moderate-to-high group estimate of metabolic intensity and had modest accuracy in identifying activity types across a variety of daily activities. However, significant between person variations were evident. Additional work is needed to refine wrist-worn accelerometers for estimating physical activity type, intensity, duration and frequency across the age spectrum.

The Interval-Based Physiological and Mechanical Demands of Cross-Country Ski Training

Purpose: To investigate fluctuations in speed, work rate, and heart rate (HR) when cross-country ski skating across varying terrains at different endurance-training intensities. Methods: Seven male junior Norwegian skiers performed maximal-speed (Vmax) tests in both flat and uphill terrains. Thereafter, 5-km sessions at low (LIT), moderate (MIT), and high intensity (HIT) were performed based on their own perception of intensity while monitored by a global navigation satellite system with integrated barometry and accompanying HR monitor. Results: Speed, HR, and rating of perceived exertion gradually increased from LIT to MIT and HIT, both for the total course and in flat and uphill terrains (all P < .05). Uphill work rates (214 [24] W, 298 [27] W, and 350 [54] W for LIT, MIT, and HIT, respectively) and the corresponding percentage of maximal HR (79.2% [6.1]%, 88.3% [2.4]%, and 91.0% [1.7]%) were higher than in flat terrain (159 [16] W, 206 [19] W, and 233 [72] W vs 72.3% [6.3]%, 83.2% [2.3]%, and 87.4% [2.0]% for LIT, MIT, and HIT, respectively) (all P < .01). In general, ∼13% point lower utilization of maximal work rate was reached in uphill than in flat terrain at all intensities (all P < .01). Conclusions: Cross-country ski training across varying terrains is clearly interval based in terms of speed, external work rate, and metabolic intensity for all endurance-training intensities. Although work rate and HR were highest in uphill terrain at all intensities, the utilization of maximal work rate was higher in flat terrain. This demonstrates the large potential for generating external work rate when uphill skiing and the corresponding downregulation of effort due to the metabolic limitations.

Allometry of mitochondrial efficiency is set by metabolic intensity

Metabolic activity sets the rates of individual resource uptake from the environment and resource allocations. For this reason, the relationship with body size has been heavily documented from ecosystems to cells. Until now, most of the studies used the fluxes of oxygen as a proxy of energy output without knowledge of the efficiency of biological systems to convert oxygen into ATP. The aim of this study was to examine the allometry of coupling efficiency (ATP/O) of skeletal muscle mitochondria isolated from 12 mammal species ranging from 6 g to 550 kg. Mitochondrial efficiencies were measured at different steady states of phosphorylation. The efficiencies increased sharply at higher metabolic rates. We have shown that body mass dependence of mitochondrial efficiency depends on metabolic intensity in skeletal muscles of mammals. Mitochondrial efficiency positively depends on body mass when mitochondria are close to the basal metabolic rate; however, the efficiency is independent of body mass at the maximum metabolic rate. As a result, it follows that large mammals exhibit a faster dynamic increase in ATP/O than small species when mitochondria shift from basal to maximal activities. Finally, the invariant value of maximal coupling efficiency across mammal species could partly explain why scaling exponent values are very close to 1 at maximal metabolic rates.

ETHNIC FEATURES OF LIPID PROFILE AND LIPID PEROXIDATION IN FREESTYLE WRESTLERS

Aim. The article deals with the assessment of the lipid profile, lipid peroxidation, and antioxidant protection in freestyle wrestlers belonging to different ethnic groups. Materials and methods. The study involved freestyle male wrestlers aged 18–22 with the rank of the Candidate for Master of Sport and Master of Sport regularly practicing freestyle wrestling. We studied a serum consisting of blood plasma and erythrocyte hemolysate. Lipid exchange was studied with the help of the BTS-350 analyzer (Spain) and BioSystems (Spain) reagents. To establish aminotransferase in blood serum, we used Vital (Russia) reagents. The components of lipid peroxidation and antioxidant protection were established with the help of spectrophotometric and fluorometric methods. Results. Freestyle athletes of the Russian ethnic group are characterized by a significantly lower TG concentrations compared to Buryat athletes. In the system of lipid peroxidation and antioxidant protection, in athletes of the Russian ethnic group, we revealed a significant AOA, reduced glutathione and retinol compared to Buryat athletes. Conclusion. The data obtained prove a different degree of metabolic activity in athletes from various ethnic groups. The balance between lipid oxidation and antioxidant protection mostly determines metabolic intensity as well as adaptation capacities of the body. The study of metabolic changes in highly-skilled athletes from different ethnic groups can contribute to the deepening of knowledge about the physiological basis and pathogenetic effects of stress on the human body. This will be one of the factors for optimizing training and providing the search for the ways of increasing physical activity as a mean of preserving the nation and sports development.