This study aimed to assess the changes in red blood cell (RBC) energy status and plasma purine metabolites concentration over a one-year training cycle in endurance-trained (EN; n = 11, 20-26 years), and sprint-trained (SP; n = 11, 20-30 years) competitive athletes in comparison to recreationally-trained individuals (RE; n = 11, 20-26 years). Somatic, physiological, and biochemical variables were measured in four training phases differing in exercise load profile: transition, general, specific, and competition. Significantly highest values of RBC adenylate energy charge (AEC; p ≤ 0.001), ATP-to-ADP and ADP-to-AMP ratios (p ≤ 0.05), and plasma levels of adenosine (Ado; p ≤ 0.05) were noted in the competition phase in the EN and SP, but not in the RE group. Significantly lowest plasma levels of adenosine diphosphate (ADP; p ≤ 0.05), adenosine monophosphate (AMP; p ≤ 0.001), inosine (Ino; p ≤ 0.001), and hypoxanthine (Hx; p ≤ 0.001) accompanied by higher erythrocyte hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity (p ≤ 0.001), were observed in the competition phase in both athletic groups. No significant alterations were found in the erythrocyte concentration of guanine nucleotides in any group. In conclusion, periodized training of competitive athletes' results in a favorable adaptation of RBC metabolism. The observed changes cover improved RBC energy status (increased AEC and ATP/ADP ratio) and reduced purine loss with more efficient erythrocyte purine pool recovery (increased HGPRT activity and plasma levels of Ado; decreased Hx and Ino concentration).Metabolites 2020, 10, 5 2 of 15 to sedentary humans, besides increased erythropoiesis, there is also observed enhanced erythrocyte turnover and an increase in the number of young red blood cells [2,3].The RBCs' vitality, resilience, and functioning rely on their energy metabolism, mainly glycolysis, which is the only source of adenosine triphosphate (ATP) in RBC [7]. Since ATP resynthesis involves multistep metabolic pathways, the amount of RBC energy resources is usually described by the concentration of ATP, adenosine triphosphate/adenosine diphosphate ratio (ATP/ADP), and the adenylate energy charge (AEC) [8].There are scant studies reporting changes in purine nucleotide catabolite concentration in human and animal erythrocytes in response to single bouts of exercise [3,[9][10][11]. The results obtained from humans suggest that both maximum- [3,9] and moderate-intensity [10] exercise do not significantly affect the total adenylate and guanylate concentration, while adenine (but not guanine) nucleotide concentration in the adenylate pool considerably changes. A substantial post-exercise decrease in adenosine diphosphate (ADP) and adenosine monophosphate (AMP) concentration leads to an increase in ATP/ADP ratio, ADP/AMP ratio, and AEC. These observations are in line with data derived from animals [11].The research conducted so far demonstrated that there were significant differences between trained and sedentary individuals in erythrocyte energetics ...

The study aimed to verify the effect of intra- (beta-alanine—BA) versus extra- (alkaline agents—ALK) cellular buffering agent supplementation, combined with customarily used branched-chain amino acids (BCAAs) and creatine malate (TCM) treatment in natural training conditions. Thirty-one elite athletes (11 sprinters and 20 endurance athletes) participated in the study. Eight-week randomized double-blind, crossover, combined supplementation with BA-ALKplaBCAA&TCM and ALK-BAplaBCAA&TCM was implemented. In the course of the experiment, body composition, aerobic capacity, and selected blood markers were assayed. After BA-ALKplaBCAA&TCM supplementation, total fat-free mass increased in sprinters (p = 0.009). No other differences were found in body composition, respiratory parameters, aerobic capacity, blood lactate concentration, and hematological indices after BA-ALKplaBCAA&TCM/ALK-BAplaBCAA&TCM supplementation. The maximum post-exercise blood ammonia (NH3) concentration decreased in both groups after BA-ALKplaBCAA&TCM supplementation (endurance, p = 0.002; sprint, p < 0.0001). Also, lower NH3 concentrations were observed in endurance athletes in the post-exercise recovery period. The results of our study indicate that combined BCAA, TCM, and BA supplementation is more effective than combined BCAA, TCM and ALK supplementation for an increase in fat-free mass and exercise adaptation, but not for aerobic capacity improvement. Besides, it seems that specific exercise stimuli and the training status are key factors affecting exercise performance, even in athletes using efficient supplementation.

The aim of the study was to investigate the reliability and construct validity of the Polish adaptation of the Community Health Activities Model Program for Seniors (CHAMPS) physical activity questionnaire among the elderly. The sample included 104 volunteers, 75 women (age = 71.0 ± 5.0 years) and 29 men (age = 75.1 ± 6.6 years). To assess the reliability of the Polish version of the CHAMPS physical activity questionnaire, measurements were conducted by one-week test-retest. The construct validity of the CHAMPS physical activity questionnaire was evaluated using accelerometers. Criterion validation was verified by self-reported measurements (health self-assessment, life satisfaction, and wellbeing) and body composition analysis. Intraclass correlation coefficients of the one-week test-retest ranged from 0.79 to 0.85. Significant Pearson’s correlations were found between caloric expenditure measured by accelerometer and CHAMPS caloric expenditure in all listed physical activities (r = 0.33) and caloric expenditure in at least moderate intensity physical activities (r = 0.37) of the CHAMPS physical activity questionnaire. Moderate and greater intensity physical activities of CHAMPS measure were significantly related to total bone mass, health self-assessment, life satisfaction as a whole, and personal wellbeing (r ranged from 0.26 to 0.34). The findings of the study allow us to conclude that the Polish version of the CHAMPS physical activity questionnaire has acceptable reliability and validity to assess physical activity of older adults.

SummaryStudy aim: To compare the blood ammonia and lactate concentrations in sprinters and triathletes during an incremental treadmill exercise test and in the 30 minutes of recovery. Material and methods:The study included 10 male sprinters and 14 male triathletes who compete at the national and international level. A treadmill test until exhaustion was administered. Blood samples for ammonia and lactate were obtained when the athletes were at rest, during and immediately after exercise, and between 5 and 30 min after exercise. Results:The ammonia concentration and time course were similar in the sprinters and triathletes (F = 1.81, p ≥ 0.05, η 2 = 0.08). An exercise-related increase in blood ammonia was almost linear, regardless of the exercise intensity. In the case of lactate, the interactions between the concentrations measured in the sprinters and triathletes were statistically significant (F = 5.78, p ≤ 0.001, η 2 = 0.21). Post-hoc tests revealed that the lactate concentrations differed significantly between the sprinters and triathletes in the 18th min (p ≤ 0.01) and the 21st min (p ≤ 0.001) of the exercise test. The blood lactate increased in a nonlinear manner (slowly at lower intensities and rapidly at higher intensities). During the 30 min recovery period, both the ammonia and lactate levels decreased linearly. However, in the sprinters, the peak values were maintained in the first stage of recovery (5 min post-exercise). Conclusions:The study showed that the blood ammonia concentration may be a useful marker of exercise-related metabolic responses in sprint-trained as well as in endurance-trained competitive athletes. Blood ammonia levels were more intensitysensitive across the whole intensity range during the incremental exercise when compared to the blood lactate levels.

Qualitative dietary assessments are not common in aging athletes. Therefore, this study aimed to evaluate diet quality and its determinants among aging masters athletes. Eighty-six participants of the 8th World Masters Indoor Athletics Championships were enrolled in the study (age range 36–65 years). Three subgroups were distinguished to represent countries with different eating habits. Body composition was measured by bioelectrical impedance. Eating habits and diet quality were assessed using the Dietary Habits and Nutrition Beliefs Questionnaire (KomPAN®, Warszawa, Poland), and the Pro-healthy Diet Index (pHDI-10). Dietary quality determinants were identified by a multiple regression model conducted for each subgroup separately (Great Britain, France, and Poland). The results showed that none of the subgroups adhered to the reference intake of products with beneficial health outcomes. This was particularly noticeable in the insufficient consumption of whole grain products, dairy, and fish. The fish and vegetables consumption frequency significantly differentiated the eating habits of the studied groups. Diet quality determinants varied depending on the group. However, in each of them, fruit consumption was one of the components of a good-quality diet. The obtained results can be used by institutions providing health education among the elderly to develop an appropriate strategy aimed at changing inappropriate eating habits.