Combined androgenic-anabolic steroids (AAS) and overloading affects tendon collagen metabolism and ultrastructure and is often associated with a higher risk of injury. The aim of this prospective study was to investigate whether such effects would be reflected in the patellar tendon properties of individuals with a history of long-term resistance training and AAS abuse (RTS group), compared with trained (RT) and untrained (CTRL) nonsteroids users. Tendon cross-sectional area (CSA), stiffness, Young's modulus, and toe limit strain were measured in vivo, from synchronized ultrasonography and dynamometry data. The patellar tendon of RT and RTS subjects was much stiffer and larger than in the CTRL group. However, stiffness and modulus were higher in the RTS group (26%, P < 0.05 and 30%, P < 0.01, respectively) than in the RT group. Conversely, tendon CSA was 15% (P < 0.05) larger in the RT group than in RTS, although differences disappeared when this variable was normalized to quadriceps maximal isometric torque. Yet maximal tendon stress was higher in RTS than in RT (15%, P < 0.05), without any statistical difference in maximal strain and toe limit strain between groups. The present lack of difference in toe limit strain does not substantiate the hypothesis of changes in collagen crimp pattern associated with AAS abuse. However, these findings indicate that tendon adaptations from years of heavy resistance training are different in AAS users, suggesting differences in collagen remodeling. Some of these adaptations (e.g., higher stress) could be linked to a higher risk of tendon injury.

While concurrent training is regularly used in older populations, the inverse relationship between fibre size and oxidative capacity suggests that endurance training in resistance-trained individuals may result in some loss of resistance training-induced gains in muscle mass, which may be more pronounced in older people. We investigated the impact of superimposed endurance training in younger (28.5 ± 4.8 years; n = 8) and older (67.5 ± 5.5 years; n = 7) highly resistance-trained men. Participants underwent a 10-week endurance cycling training programme consisting of five 6-min intervals at 75% max heart rate (HRmax) separated by 4-min intervals at 90% HRmax. The anatomical cross-sectional area (ACSA) of the thigh muscles, as determined with MRI, was 24% smaller in older compared to younger participants (p < 0.001). Although maximal oxygen consumption (VO2max) was also lower in the older group (p < 0.001), VO2max per kg body mass did not differ significantly between younger and older participants. Histological analyses of biopsies of the m. vastus lateralis showed that endurance training induced an increase in succinate dehydrogenase activity in both younger and older participants (p ≤ 0.043), and an increase in the number of capillaries around type I fibres (p = 0.017). The superimposed endurance training did not induce a significant decrease in thigh ACSA, fibre cross-sectional area, or knee extensor maximum voluntary isometric force. These observations indicate that adding endurance training to resistance training can lead to positive endurance-related adaptations without negative consequences for muscle size and strength in older and younger resistance-trained people.

Background Recent evidence indicates that elevating plasma nitrites through dietary nitrates (NO 3 − ) supplementation is associated with enhanced muscle efficiency, fatigue resistance and performance. Beetroot (in various forms) is the dominant source of dietary NO 3 − primarily due to its vast availability and the simple form of preparation suitable for final consumption. After a few years of research and experimentation, our scientific team identified alternative source rich with dietary NO 3 − as possible nitric oxide precursor, amaranth ( Amaranthus hypochondriacus ) with a standardized concentration 9–11% of NO 3 − . This study aimed to evaluate the effect of single-dose (±400 mg of dietary NO 3 − ) and long-term (6 days) supplementation of amaranth concentrate derived dietary NO 3 − on aerobic capacity in physically active young people. Methods We conducted a randomized, double-blind, placebo-controlled human study. Thirteen healthy and physically active young male participants were randomized into experimental and placebo groups. The aerobic capacity was tested during increasing cycling exercise (ICE) with pulmonary gas exchange recording and analysis. Results The peak power of the ICE, the maximum oxygen consumption and the first ventilatory threshold were significantly increased after long-term consumption of dietary amaranth (from 4.44 ± 0.50 to 4.55 ± 0.43 W/kg; from 37.7 ± 2.7 to 41.2 ± 5.4 mL/kg/min and from 178.6 ± 30.3 to 188.6 ± 35.2 W, p < 0.05; respectively) in experimental group. Conclusions Long-term (6 days) use of dietary NO 3 − from amaranth may improve the aerobic capacity during ICE in young physically active male persons. It can be recommended as the nutritional supplement during last week of preparation for competition in endurance events.

Over the past five years, the popularity of dietary nitrates as an ergogenic device among athletes has increased significantly. Hypoxic and acidic conditions that occur during exercise facilitate the conversion of nitrite to nitric oxide (NO) and increase the physiological efficiency of exogenously produced nitrite. After a few years of our team predicted experiments, as a nitric oxide precursor, amaranth (Amaranthus hypochondriacus) was identified as a source of dietary nitrates (concentrations 9-11%). The aim of this study was to evaluate the effect of single-dose and long-term doses of dietary nitrates from amaranth concentrate on the aerobic capacity of physically active young persons. Thirteen healthy and physically active young participants were randomized to experimental and placebo groups using a increasing cycling exercise (ICE) and placebo-controlled design. Pulmonary gas exchange recording (oxygen uptake (VO2), pulmonary ventilation (VE), respiratory exchange ratio (RER)) and analysis of blood lactate samples were obtained. Our findings indicate that the single dose of dietary amaranth (400 mg) significantly improved only the power of the test performance. Long-term (6 days) intake significantly increased the power of the test performance, the maximum oxygen consumption and the power of the test for the first ventilation threshold value (from 37.7±2.7 mL/kg/min during the first test to 41.2±5.4 mL/kg/min during the third test, p <0.05).

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