Enrico Rejc

Background: Sarcopenic obesity (SO) is a clinically relevant but often under-recognized condition in older adults. This study examined whether obesity severity and body fat distribution are associated with physical capacity, functional autonomy and health-related quality of life in a sex-specific manner. Methods: In this observational case–control study with cross-sectional assessments, 45 older obese adults (OB; 27 men and 18 women) and 40 non-obese (NOB) comparison participants (18 men and 22 women), aged 65–85 years, underwent anthropometric assessment, bioelectrical impedance analysis, geometric body shape indexing, physical performance testing, autonomy assessment, physical activity evaluation and health-related quality-of-life assessment. SO was classified using a study-specific operational application of the ESPEN/EASO framework based on excess adiposity, impaired muscle function, and BIA-derived skeletal muscle mass adjusted for body mass. Results: Using this operational framework, all participants in the OB group were classified as presenting an SO phenotype. OB men showed substantially greater visceral adipose tissue mass than OB women (+106.5%, ES: 1.27, large, p < 0.001) and a higher A body shape index-associated relative risk (+27.9%, ES: 0.82, large, p < 0.001). Conversely, OB women showed more severe mobility impairment than OB men, with lower performance in the 8-Foot Up-and-Go (−22.9%, ES: 0.66, medium, p < 0.001) and 6-Min Walk test (−23.4%, ES: 0.64, medium, p < 0.001) and slightly lower basic autonomy. Health-related quality of life was significantly reduced only in OB men (−10.8%, ES: 1.07, large, p < 0.001) than NOB. Conclusions: In this clinical sample, an operational SO phenotype was identified among older OB adults and exhibited divergent sex-specific profiles. Men showed a predominantly geometric visceral risk phenotype and poorer perceived health status, whereas women showed more pronounced impairment in mobility and basic functional autonomy. These findings support sex-differentiated, multidisciplinary rehabilitation strategies in older adults with obesity.

Background: Anorexia Nervosa (AN) triggers profound metabolic and psychological adaptations during adolescence. This study investigated the relationships between resting energy expenditure (REE), body composition, physical activity (PA), and specific psychometric phenotypes in adolescent girls with AN compared to healthy, normal-weight (NW) peers. Methods: Sixteen adolescent girls with severe AN (16.1 ± 1.2 year) and 16 age-matched NW controls (15.6 ± 1.5 year) underwent clinical evaluations: anthropometry, bioelectrical impedance analysis for fat-free mass (FFM) and fat mass (FM), indirect calorimetry for REE, the short-form International Physical Activity Questionnaire (IPAQ), and the Eating Disorder Inventory-3 (EDI-3). Results: Girls with AN exhibited significantly lower BMI (−20.3%, ES: 1.94, large), FFM (−18.3%, ES: 1.92, large), and FM (−25.7%, ES: 0.79, medium) than controls (p < 0.003). Absolute REE was drastically lower (−40.4%, ES: 3.53, large, p < 0.001). This hypometabolic state persisted after adjusting REE for body weight (−34.9%) or FFM (−32.5%, p < 0.001), consistent with adaptive thermogenesis. The AN group displayed resting hypotension and 79.0% (ES: 1.84, large, p < 0.001) lower total PA energy expenditure due to a lack of structured moderate-to-vigorous exercise; however, walking expenditure did not differ. Psychometrically, the AN cohort showed significantly higher (p < 0.001) values for drive for thinness (+316.9%, ES: 3.16, large), body dissatisfaction (+232.3%, ES: 2.30, large), and severe general psychological maladjustment, including higher interoceptive deficits (+148.2%, ES: 1.26, large). Conclusions: Adolescents with AN exhibit profound metabolic suppression via adaptive thermogenesis, together with an apparent dissociation between walking-related activity and hypotension. Since cognitive distortions and distress vary independently of anthropometric severity, clinical recovery must extend beyond nutritional rehabilitation; targeted psychotherapy may therefore be necessary to address persistent psychological maladjustment.

Background: Neuromuscular deficits may persist following anterior cruciate ligament reconstruction (ACLR), even after returning to sport. In this exploratory case series, we investigated the effects of non-invasive spinal cord transcutaneous stimulation (scTS), applied during warm-up for approximately 25 min to prime the nervous system, on neuromuscular performance of the ACLR limb during a simulated half-squat power training session. Methods: Four young, non-professional athletes with time since ACLR between 9.0 and 14.5 months, who were already returned to sport, participated in this study. Force, velocity, power, and electromyography of representative thigh muscles generated by the ACLR and intact limbs during unilateral half-squats on a Smith machine, were assessed over two separate experimental sessions (scTS or sham stimulation priming). Results: Three of the four participants showed power deficit in the ACLR limb during the concentric phase. scTS priming promoted higher power output generated by the ACLR limb in these three participants. Oscillatory-like force pattern during the downward phase was more prominent in the ACLR limb for one subject, and scTS priming attenuated it. Conclusions: These findings support future controlled trials to assess the efficacy of scTS priming as an aid to enhance rehabilitation and physical training after ACLR.

BACKGROUND Balance control relies on proprioceptive, visual and vestibular inputs, contributing to functional performance and injury prevention. Neuromodulation strategies targeting the spinal circuitry controlling lower limbs are emerging as potential approaches to enhance lower limb neuromuscular performance. For example, non-invasive lumbosacral spinal cord transcutaneous stimulation (scTS) applied to prime the nervous system can improve lower limb performance during repeated, high-level efforts. However, it is unclear whether such neural priming approach can influence low-level motor outcomes and balance control. AIM To assess the effects of scTS priming on single-leg stance balance control with and without visual input. METHODS Twelve young active males (age: 22.7 ± 2.1 years) participated in this randomized crossover, sham-controlled study. Single-leg stance balance control with eyes open and eyes closed was assessed before and after the priming protocol with scTS or sham stimulation for approximately 25 minutes over a total of two different experimental sessions. Anterior-posterior, medio-lateral and a composite of the two directions were assessed on the force platform as well as electromyography of tibialis anterior (TA) and medial gastrocnemius muscles. RESULTS Priming protocols with scTS or sham application did not influence single-leg stance performance, as reflected by trial duration, kinetic and electromyography outcomes (priming effect: P -values ranging from 0.343 to 0.759). A significant effect of vision emerged, with shorter trial duration (P = 0.018), larger anterior-posterior (P = 0.004), medio-lateral (P < 0.001) and total displacement (P < 0.001), as well as longer co-contraction between TA and medial gastrocnemius (P < 0.001) with eyes closed compared to eyes open. Also, a time × priming × eyes interaction was found for the TA muscle activation (P = 0.046), indicating increased TA activation at the end vs beginning of eyes open trials following scTS priming. CONCLUSION The scTS priming did not affect single-leg stance balance performance under both eyes closed and open conditions. Also, as expected, impaired balance control was found with eyes closed.

Obesity is a chronic disease characterized by excessive fat accumulation. Irisin, released during exercise, regulates energy metabolism and may contribute to exercise-induced metabolic adaptations. This study aimed to compare the effects of 24 weeks of two different training programs on body composition, physical capacities, and irisin levels in male adults with obesity, and to investigate the relationship between irisin and metabolic parameters. Thirteen male adults with obesity were randomly assigned to polarized (POL) or threshold (THR) training programs. Anthropometric measurements, physical capacity parameters, serum and salivary samples were collected before (T0) and after the training period (T1). Irisin levels were measured by ELISA. After training, body composition significantly improved, with reductions in body mass and body mass index, and an increase in fat-free mass. Maximal oxygen consumption (V’O₂max) significantly increased, while a decrease in HRmax indicated improved cardiac efficiency. Although serum and salivary irisin levels did not significantly increase overall, a trend toward increased irisin was observed in the THR group. Furthermore, serum irisin at T1 positively correlated with V’O₂ at the respiratory compensation point (p = 0.019), and V’O₂max (p = 0.031). Both POL and THR training programs significantly improved body composition and cardiometabolic fitness after 24 weeks. The positive association of irisin with aerobic fitness parameters suggests that irisin may reflect physiological adaptations to exercise.

Aging induces sarcopenia and reduces bone mineral density, altering body composition. These modifications contribute to physical decline, increase non-communicable disease risk and increase the likelihood of hospitalization, thereby representing a substantial public health burden. In this study, we assessed the effects of isometric training with neuromuscular electrical stimulation conditioning contractions (ISO-NMES) and dynamic resistance training (DRT) on physical and functional capacities. Moreover, we investigated the impact of ISO-NMES training on the force and power of the trained and untrained leg. Eighteen sessions of ISO-NMES training for knee extensors were performed by 10 older adults (age: 70.1 ± 4.9 years; ISO-NMES group). The DRT group (n = 12; age: 70.5 ± 2.8 years) performed 18 sessions of dynamic resistance training at a local fitness center. Maximum voluntary contraction (MVC) and peak power (P) of lower limbs as well as functional capacities assessed with the 5 Sit to Stand, Timed Up and Go and 6 Minutes Walking Tests were examined in both groups before and after the related training protocols. At the end of the training period, only the ISO-NMES group had improved MVC (+30.4%, p < 0.001) and bilateral force (ISO-NMES: +6.3%, p = 0.032). Moreover, both groups had significantly improved functional capacities. Finally, in the ISO-NMES group, MVC, force and power significantly increased in both legs with a greater effect for MVC in the trained than untrained leg (+30.4 vs. +13.5%, p < 0.001). These findings suggest that ISO-NMES training was an effective strategy to improve physical and functional capacities in older adults. Thus, it could be considered as a potential intervention, particularly when the mobility to perform physical training is limited.

Purpose : Traditional training metrics do not distinguish between the different components of internal training load contributing to training-induced fatigue, whereas the National Aeronautics and Space Administration Task Load Index (NASA-TLX) may offer a compelling multidimensional alternative. However, the NASA-TLX subscales have been overlooked in the context of endurance training. Therefore, this study investigated whether the NASA-TLX subscales are associated with acute performance decrement (APD) and physiological responses across different endurance training sessions. Methods : Twelve well-trained runners (10 males, 2 females; age 26.8 [6.9] y; maximal oxygen uptake [VO ₂ max] 65.6 [6.4] mL·kg ⁻¹ ·min ⁻¹ ) completed 6 visits in the laboratory, an incremental test, a time to exhaustion (TTE) test, and 4 experimental training sessions in randomized order. A TTE test was performed at baseline and after each of 4 exercise sessions: low-intensity training, medium-intensity training, long-interval high-intensity (HIT _long ), and short-interval high-intensity (HIT _short ). APD was calculated as the percentage drop in TTE compared to baseline. The NASA-TLX questionnaire was administered between each training session and the TTE test to assess mental demand, physical demand, temporal demand, effort, frustration, and perceived performance. Results : All sessions led to significant APD ( P = .041), with HIT _long producing greater APD than low-intensity training ( P = .035). Subscale analysis showed lower mental, physical, temporal, and effort scores after low-intensity training compared to HIT sessions ( P < .001). All subscales were significantly correlated with APD and key physiological ventilatory and metabolic parameters ( P < .001). Conclusion : NASA-TLX subscales appear valid and may help athletes to discriminate distinct components of perceived workload.

Purpose: To investigate the potential efficacy of spinal cord transcutaneous stimulation (scTS) priming to enhance lower limb neuromuscular performance during a subsequent power training session. Methods: Eleven young active males (age: 21.3 ± 1.6 yr) participated in this randomized crossover, sham-controlled study. The priming protocol consisted of the application of scTS or sham stimulation (Sham) at rest and during warm-up for approximately 25 min. Force, velocity, and power, as well as electromyography (EMG) of lower limbs generated during unilateral half squats on a Smith machine, were assessed over two separate experimental sessions (scTS or Sham) for: 1) four power training sets, each including six unilateral repetitions with 2) the last (fourth) set continuing to failure. Results: Peak and mean power generated during the four power training sets preceded by scTS priming were significantly higher (11%, P < 0.001 and 14%, P = 0.008, respectively) than those generated in the Sham session. Similar trends were also shown by velocity, force, and total impulse of force. Exploratory EMG analysis revealed that scTS priming favored an overall improved activation of the vastus lateralis during the concentric phase. Higher peak and mean power outputs (13%, P = 0.006, and 24%, P = 0.014, respectively), associated with higher EMG amplitude of vastus lateralis, were promoted by scTS priming also for the last set to failure, which resulted in a similar number of repetitions between the scTS (32 ± 17) and Sham priming (32 ± 19) sessions. Conclusions: scTS priming enhanced neuromuscular outcomes during a simulated lower limb power training session. Further studies should implement scTS priming throughout a longitudinal power training intervention and assess its potential to enhance training-induced neuromuscular adaptations.

Background: Lower limb motor output contributes to determining functional performance in many motor tasks. This study investigated the effects of non-invasive spinal cord transcutaneous stimulation (scTS) applied during an exercise-based priming protocol on lower limb muscle force and power generation. Methods: Twelve young, physically active male volunteers (age: 22.7 ± 2.1 years) participated in this randomized crossover, sham-controlled study. The maximal voluntary contraction and low-level torque steadiness of knee extensors, as well as the maximal explosive extension of lower limbs, were assessed before and after the priming protocol with scTS or sham stimulation over a total of four experimental sessions. Further, characteristics of evoked potentials to scTS related to spinal circuitry excitability were assessed in the supine position before and after the scTS priming protocol. The exercise component of the ~25 min priming protocol consisted of low-volume, low- and high-intensity lower limb motor tasks. Results: scTS priming protocol tended to increase or maintain maximum isometric torque during knee extension (4.7%) as well as peak force (0.2%) and rate of force development (6.0%) during explosive lower limb extensions, whereas sham priming protocol tended to decrease them (−4.3%, −3.3%, and −15.1%, respectively). This resulted in significant interactions (p = 0.001 to 0.018) and medium–large differences between scTS and sham protocols. These findings were associated with meaningful trends of some neurophysiological variables. Conversely, priming protocols did not affect low-level torque steadiness. Conclusions: scTS counteracted the unexpected fatigue induced by the exercise-based priming protocol, supporting lower limb performance during maximal efforts. Future studies are warranted to assess the implementation of scTS with optimized exercise-based priming protocols during training and rehabilitation programmes that include high-intensity neuromuscular efforts.