Aerobic and Anaerobic Power Distribution During Cross-Country Mountain Bike Racing.

PURPOSE: To determine aerobic and anaerobic demands of mountain bike cross-country racing. METHODS: Twelve elite cyclists (7 males; V˙O2max = 73.8 [2.6] mL·min-1·kg-1, maximal aerobic power [MAP] = 370 [26] W, 5.7 [0.4] W·kg-1, and 5 females; V˙O2max = 67.3 [2.9] mL·min-1·kg-1, MAP = 261 [17] W, 5.0 [0.1] W·kg-1) participated over 4 seasons at several (119) international and national races and performed laboratory tests regularly to assess their aerobic and anaerobic performance. Power output, heart rate, and cadence were recorded throughout the races. RESULTS: The mean race time was 79 (12) minutes performed at a mean power output of 3.8 (0.4) W·kg-1; 70% (7%) MAP (3.9 [0.4] W·kg-1 and 3.6 [0.4] W·kg-1 for males and females, respectively) with a cadence of 64 (5) rev·min-1 (including nonpedaling periods). Time spent in intensity zones 1 to 4 (below MAP) were 28% (4%), 18% (8%), 12% (2%), and 13% (3%), respectively; 30% (9%) was spent in zone 5 (above MAP). The number of efforts above MAP was 334 (84), which had a mean duration of 4.3 (1.1) seconds, separated by 10.9 (3) seconds with a mean power output of 7.3 (0.6) W·kg-1 (135% [9%] MAP). CONCLUSIONS: These findings highlight the importance of the anaerobic energy system and the interaction between anaerobic and aerobic energy systems. Therefore, the ability to perform numerous efforts above MAP and a high aerobic capacity are essential to be competitive in mountain bike cross-country.

Effects of acute resistance exercise on proteolytic and myogenic markers in skeletal muscles of former weightlifters and age-matched sedentary controls.

BACKGROUND: Former athletes who continue a regular, performance-oriented training throughout life provide a unique model for studying successful aging. With this in mind, the current study aimed to compare the effects of an acute resistance exercise on proteolytic and myogenic markers in older weightlifters and untrained participants. METHODS: Sixteen older men (8 former weightlifters, 8 age-matched untrained controls) with an age of 61.2±8.2 years volunteered to participate in the study. Two days after assessing 1-RM, an acute exercise protocol (3 sets, 70-75% of one-repetition maximum until voluntary fatigue) was applied unilaterally on the dominant leg while the other leg served as control. Three hours after termination of the exercise, skeletal muscle tissue was obtained from m. vastus lateralis of both legs. RESULTS: Acute resistance exercise led to an up-regulation (>1.5-fold) of 14 genes in controls and of 13 genes in weightlifters. The transcription factors FOS and early growth response 1 (EGR1), as well as the E3 protein ligase TRIM63 comprised the most responsive genes to resistance exercise (EGR1:15.7-fold increase, P=0.003, FOS: 36.3-fold increase, P<0.001; TRIM63: 2.9-fold increase, P<0.001). In addition, myostatin levels were decreased in the exercised leg (0.6-fold, P<0.001). FOXO3 gene expression was significantly higher in weightlifters than in untrained controls (1.5-fold, P=0.042). CONCLUSIONS: Trained and untrained older adults respond to an acute bout of resistance exercise in a very similar way irrespective of training status, although some differences exist in FOXO3, potentially reflecting the superior capacity of trained persons in regulating cellular homeostasis.

Acute Effects of Back Squats on Countermovement Jump Performance Across Multiple Sets of a Contrast Training Protocol in Resistance-Trained Men.

Bauer, P, Sansone, P, Mitter, B, Makivic, B, Seitz, LB, and Tschan, H. Acute effects of back squats on countermovement jump performance across multiple sets of a contrast training protocol in resistance-trained men. J Strength Cond Res 33(4): 995-1000, 2019-This study was designed to evaluate the voluntary postactivation potentiation (PAP) effects of moderate-intensity (MI) or high-intensity (HI) back squat exercises on countermovement jump (CMJ) performance across multiple sets of a contrast training protocol. Sixty resistance-trained male subjects (age, 23.3 ± 3.3 years; body mass, 86.0 ± 13.9 kg; and parallel back squat 1-repetition maximum [1-RM], 155.2 ± 30.0 kg) participated in a randomized, crossover study. After familiarization, the subjects visited the laboratory on 3 separate occasions. They performed a contrast PAP protocol comprising 3 sets of either MI (6 × 60% of 1-RM) or HI back squats (4 × 90% of 1-RM) or 20 seconds of recovery (CTRL) alternated with 7 CMJs that were performed at 15 seconds, and 1, 3, 5, 7, 9 and 11 minutes after the back squats or recovery. Jump height and relative peak power output recorded with a force platform during MI and HI conditions were compared with those recorded during control condition to calculate the voluntary PAP effect. Countermovement jump performance was decreased immediately after the squats but increased across all 3 sets of MI and HI between 3 and 7 minutes after recovery. However, voluntary PAP effects were small or trivial, and no difference between the 3 sets could be found. These findings demonstrate that practitioners can use MI and HI back squats to potentiate CMJs across a contrast training protocol, but a minimum of 3 minutes of recovery after the squats is needed to benefit from voluntary PAP.

Eccentric resistance training intensity may affect the severity of exercise induced muscle damage.

BACKGROUND: The aim of the present study was to assess the role of eccentric exercise intensity in the development of and recovery from delayed onset muscle soreness (DOMS). METHODS: Using a cross-over study design, 15 healthy, male college students were tested on two occasions. The training stimulus consisted of an exhaustive series of eccentric muscle contractions of the elbow flexors at either 100% (high intensity) or 50% (low intensity) of the individual concentric one-repetition maximum. Blood samples were taken at baseline as well as 24, 48, 72 and 96 hours postexercise, and analyzed for creatine kinase, myoglobin, interleukin-6 and prostaglandin-2. Additionally, upper arm circumference (CIRC) and DOMS-related sensation of pain (PAIN) were measured. RESULTS: Following high intensity training, CIRC was significantly greater (P=0.007). Further, creatine kinase, myoglobin and interleukin-6 tended to be higher, although the main effect of the factor "intensity" just failed to reach significance (creatine kinase: P=0.056, myoglobin: P=0.064, interleukin-6: P=0.091). No differences were found for prostaglandin-2 (P=0.783) and PAIN (P=0.147). CONCLUSIONS: When performed at greater intensity, fatiguing eccentric resistance exercise of the elbow flexors leads to greater muscle swelling and, potentially, increases in serum markers reflecting lesions in the muscle's cellular membrane.

Musculoskeletal Health of 40-65 Year Old Males and Females in Kosova and the Impact of N05B, A02B (PPI, H2RA), H02AB and Lifestyle Factors on It.

BACKGROUND: This observational, cross-sectional study investigates the impact of medication usage, physical activity (PA) and nutritional status on musculoskeletal health (MSH) in males and females aged 40-65 in the population of a post conflict, developing country. METHODS: Bone Mineral Density (BMD), T-score and Z-score at distal forearm regions (measured by DEXA scan), together with isometric hand grip strength (dynamometer) were evaluated in a total of 162 subjects (53 Males, average age 55.15±7.12 and 109 Females, 54.27±5.1). Additionally, bio-anthropometric assessments, medication usage, PA level and nutritional status were assessed. RESULTS: Significant differences (p<0.05) were found in total subjects Body Mass Index (BMI), PA, BMD, T-score and Hand grip between genders. 42% of total participants met the diagnostic criteria of, out of which 6.8% with T-score below -2, while no cases of Osteoporosis was recorded. N05B Anxiolytics and A02B Drugs for peptic ulcer and gastro-oesophageal reflux disease medication groups consumption turned to have no significant differences (p>0.05) in BMD, T-score, and hand grip in total population, except for A02B where p<0.05 were found in Hand grip, as well as between female consumers and no consumers in all variables. Meanwhile, in total subjects consuming H02AB Glucocorticoids p<0.05 were observed in BMD and T-score, but not on hand grip. CONCLUSIONS: This study shows a low risk for MSH problems amongst the studied population in Kosova, while the consumption of H02AB medication group in both genders and A02B in females only for extended periods might effect MSH, therefore appropriate benefit/risk assessment should be made before prescribing these medications, notwithstanding age, gender, PA or nutritional status.

Influence of age and physical fitness on miRNA-21, TGF-ß and its receptors in leukocytes of healthy women.

The TGF-ß superfamily has been shown to play an important role in a wide range of physiological as well as pathological processes including ageing, immune modulation, atherosclerosis and cancer development. The aim of the current study was to investigate (i) whether TGF-ß signalling in peripheral blood mononuclear cells (PBMCs) would differ between young and old females and (ii) whether physical performance parameters of elderly women would be related to the expression of TGF-ß or its receptors. Sixteen healthy young (22-28 years; YF) and 90 healthy older (65-92 years; OF) females participated in the study. In addition to several components of health-related physical fitness, circulating CRP and TGF-ß levels were determined together with the mRNA expression of TGF-ß, TGF-ßRI, TGF-ßRII, and miRNA-21 (known to interfere with TGF-ß signalling) in PBMCs. Physical fitness as determined by 6-minutes walking test (YF:median 932 (range 573-1254) m; OF:360 (114-558) m), handgrip strength (YF: 32 (24-39) kg; OF:18(10-30) kg), relative isokinetic peak torque of knee extensors (YF:1.9 (1.2- 2.3) Nm/kg; OF:1.0 (0.2-1.9) Nm/kg and flexors (YF: 1.1 (0.7- 1.5) Nm/kg; OF: 0.5 (0.2-1.0) Nm/kg was substantially lower in older women (p<0.001 for all comparisons). These changes were paralleled by an increase in hs-CRP (YF: 0.9 (0.1-4.3)mg/L; OF: 2.3 (0.3-56.7)mg/L,p<0.001). Serum levels of TGF-ß and TGF-ß mRNA levels from PBMCs did not differ between young and old women whereas, both TGF- ßRI/GAPDH (YF: 4.07 (1.38-14.60); OF: 2.08 (0.14-28.81); p=0.020) and TGF-ßRII/GAPDH levels (YF: 3.16 (1.14- 10.25); OF: 1.71 (0.51-14.86); p=0.020) were lower with respect to old age. In elderly women, only TGF-ßRΙ expression correlated negatively with miRNA-21 expression in PBMCs (ρ=-0.315; p=0.004). Interestingly, hs-CRP and miRNA correlated positively with handgrip strength (ρ=0.237 and ρ=243, p<0.05), while none of the TGF-ß-related parameters were related to physical performance. The results suggest that age affects TGF-ß signalling in leukocytes by altering the expression levels of its receptors. These changes seem to occur independently of physical fitness of old women.

A single nucleotide polymorphism associates with the response of muscle ATP synthesis to long-term exercise training in relatives of type 2 diabetic humans.

OBJECTIVE: Myocellular ATP synthesis (fATP) associates with insulin sensitivity in first-degree relatives of subjects with type 2 diabetes. Short-term endurance training can modify their fATP and insulin sensitivity. This study examines the effects of moderate long-term exercise using endurance or resistance training in this cohort. RESEARCH DESIGN AND METHODS: A randomized, parallel-group trial tested 16 glucose-tolerant nonobese relatives (8 subjects in the endurance training group and 8 subjects in the resistance training group) before and after 26 weeks of endurance or resistance training. Exercise performance was assessed from power output and oxygen uptake (VO(2)) during incremental tests and from maximal torque of knee flexors (MaxT(flex)) and extensors (MaxT(ext)) using isokinetic dynamometry. fATP and ectopic lipids were measured with (1)H/(31)P magnetic resonance spectroscopy. RESULTS: Endurance training increased power output and VO(2) by 44 and 30%, respectively (both P < 0.001), whereas resistance training increased MaxT(ext) and MaxT(flex) by 23 and 40%, respectively (both P < 0.001). Across all groups, insulin sensitivity (382 ± 90 vs. 389 ± 40 mL · min(-1) · m(-2)) and ectopic lipid contents were comparable after exercise training. However, 8 of 16 relatives had 26% greater fATP, increasing from 9.5 ± 2.3 to 11.9 ± 2.4 µmol · mL(-1) · m(-1) (P < 0.05). Six of eight responders were carriers of the G/G single nucleotide polymorphism rs540467 of the NDUFB6 gene (P = 0.019), which encodes a subunit of mitochondrial complex I. CONCLUSIONS: Moderate exercise training for 6 months does not necessarily improve insulin sensitivity but may increase ATP synthase flux. Genetic predisposition can modify the individual response of the ATP synthase flux independently of insulin sensitivity.

Effects of ultra-marathon on circulating DNA and mRNA expression of pro- and anti-apoptotic genes in mononuclear cells.

We investigated the effects of an ultra-marathon on cell-free plasma DNA as well as on mRNA expression of pro-apoptotic (Bax, Bad), anti-apoptotic (Bcl-2) and cell-protective (Hsp70, Hsp27 and Hsp32) genes in mononuclear blood cells (MNCs). Blood samples were drawn from 14 athletes before and immediately after 6-h run. In addition, blood samples were also collected and analyzed 2 and 24 h after the end of the run. Levels of plasma DNA were significantly increased immediately after the marathon (P < 0.001) and were still higher 2 h later (P < 0.005), but significantly lower than those immediately after the race (P < 0.05). Cell-free plasma DNA returned to pre-race levels 24 h after the run. mRNA expressions of Hsp70, Hsp32 and Bax significantly increased in MNCs after the race, whereas Hsp27 and Bad mRNA expression levels showed no significant changes. Bcl-2 expressions decreased immediately after the race (P < 0.001), but increased in the 24 h later (P < 0.05). We conclude that apoptotic ladders of cell-free DNA following exhaustive exercise originate from apoptotic cells and that not only skeletal muscle cells but also leukocytes contribute to this phenomenon.

Respiratory gas exchange and lactate measures during competitive orienteering.

PURPOSE: In the past, orienteering sports analyses were based on heart rate (HR) and lactate (LA) measures. This study assessed additional respiratory gas exchange measures (RGEM) to provide further information regarding the physiological requirements of orienteering competitions (OTC). METHODS: Eleven elite male athletes performed simulated OTC. RGEM were performed using a portable system. LA was determined after each section (total of six) of OTC. Athletes were also subjected to treadmill testing (TT). RESULTS: Average values for the entire OTC were [OV0312]O(2OTC): 56.4 +/- 4.5 mL.kg-1.min-1 (83.0 +/- 3.8% of [OV0312]O(2max) of TT), HR(OTC): 172 +/- 11 bpm, and LA(OTC): 5.16 +/- 1.5 mmol.L-1. The highest measured [OV0312]O(2OTC) of an athlete in this study was 64.4 +/- 2.9 mL.kg-1.min-1. [OV0312]O(2OTC) was 94.6 +/- 5.2% of [OV0312]O(2IAT) (IAT= individual anaerobic threshold), HR(OTC) was 98.0 +/- 2.9% of HR(IAT), respiratory exchange ratio was 97 +/- 3.8% and LA(OTC) was 143.9 +/- 24.2% of LA(IAT). In contrast to [OV0312]O(2) and LA, average HR were similar in all sections of OTC despite topographical differences of the course. No correlations were found between running time of OTC and variables of endurance performance. Running time correlated with running distance (P < 0.001; r = 0.83) and running speed (r = 0.98; P < 0.001). CONCLUSION: 1) Energy requirements during OTC were derived predominately via aerobic metabolism. 2) The highest [OV0312]O(2OTC) value of 64.4 mL.kg-1.min-1 may be regarded as the reference for intensities of OTC. 3) During OTC, most athletes avoid high-intensity periods of long duration. 4) Performance in OTC was essentially influenced by technical abilities. 5) Using only LA for evaluation may lead to overestimation of energy demands during OTC. 6) HR measures were not sufficiently sensitive to ascertain energy requirements of the OTC. Therefore, RGEM provided additional information regarding energy expenditure of OTC compared with LA and HR measures alone.

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles.

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (VO(2)max): 57.3 (5.1) ml.kg(-1).min(-1)] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; VO(2)max: 67.9 (3.8) ml.kg(-1).min(-1)] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average VO(2) was considerably lower [29.1 (5.6) ml(.)kg(-1.)min(-1)] or 51.1 (10.9)% of VO(2)max and 64.8.0 (13.3)% of VO(2) determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol.l(-1)]. The highest average VO(2 )value for a whole game was 47.8 ml.kg(-1.)min(-1) and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominantly via aerobic mechanism of energy delivery. During OTC, we found an average VO(2) of 56.4 (4.5) ml.kg(-1).min(-1) or 83.0 (3.8)% of VO(2)max and 94.6 (5.2)% of VO(2) at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol.l(-1)) although the average VO(2) was significantly lower than VO(2) at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of requirements of sports and assist in the optimization and interpretation of training in athletes.