Moritz Schumann

Acute Neuromuscular and Endocrine Responses and Recovery to Single-session Combined Endurance and Strength Loadings: “order Effect” in Untrained Young Men

Abstract Schumann, M, Eklund, D, Taipale, RS, Nyman, K, Kraemer, WJ, Häkkinen, A, Izquierdo, M, and Häkkinen, K. Acute neuromuscular and endocrine responses and recovery to single-session combined endurance and strength loadings: “Order effect” in untrained young men. J Strength Cond Res 27(2): 421–433, 2013—The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using 2 loading orders. Forty-two men were demographically matched to perform a single session of combined endurance + strength (E + S) or strength + endurance (S + E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength, and hypertrophic loads with an overall duration of 30 minutes. The endurance loading was conducted on a bike ergometer and performed by continuous cycling over 30 minutes at 65% of subject’s individual maximal watts. Both loading conditions led to significant acute reductions in maximal force production (E + S: −27%, p < 0.001; S + E: −22%, p < 0.001), rapid force produced in 500 milliseconds (E + S: −26%, p < 0.001; S + E: −18%, p < 0.001), and countermovement jump height (E + S: −15%, p < 0.001; S + E: −12%, p < 0.001), whereas no significant differences between the 2 loadings were observed. Maximal and explosive force production recovered after 48 hours after both loading conditions. Whereas no significant acute responses were found in concentrations of serum testosterone (T) and thyroid-stimulating hormone in the 2 loading conditions, concentrations of T were significantly reduced in E + S during recovery at 24 hours (−13%, p < 0.05) and 48 hours (−11%, p = 0.068), but not in S + E, and concentrations of thyroid-stimulating hormone significantly reduced after both loading conditions (24 hours: E + S, −32%, p < 0.001; S + E, −25%, p < 0.01; 48 hours: E + S, −25%, p < 0.001; S + E, −18%, p < 0.01). The loading conditions in this study showed that neuromuscular performance recovered already within 2 days, whereas endocrine function, observed particularly by decreased concentrations in serum T after the E + S loading order, remained altered still after 48 hours of recovery. These results emphasize the different needs for recovery after 2 loading orders.

Effects of resistance training frequency on cardiorespiratory fitness in older men and women during intervention and follow-up

Abstract This study investigated the effects of resistance training (RT) performed with different frequencies, including a follow‐up period, on cardiorespiratory fitness in healthy older individuals. Eighty‐eight men and women (69 ± 3 years, 167 ± 9 cm and 78 ± 14 kg) were randomly placed into four groups: training one‐ (M1 = 11, W1 = 12), two‐ (M2 = 7, W2 = 14), or three‐ (M3 = 11, W3 = 13) times‐per‐week or a non‐training control group (MCon = 11, WCon = 9). During months 1–3, all subjects trained two‐times‐per‐week while during the subsequent 6 months, training frequency was set according to the group. Oxygen consumption (cycling economy: CE), gross efficiency (GE), blood lactate concentrations (La) and heart rate (HR) were evaluated during a submaximal cycle ergometer test. Hemoglobin (Hb), hematocrit (Hct), heart rate (HRrest) and body composition by DXA were also measured at rest. Maximal strength was measured by a 1‐RM leg press test. Most improvements in CE, GE, La and HR occurred in all groups during months 1–3. No additional statistically significant improvements were observed during months 4–9, although effect sizes for the change in CE and GE at higher workloads indicated a dose‐response pattern in men (CE at 75 W: M1 g = 0.13, M2 g = −0.58, M3 g = −0.89; 100 W: M1 g = 0.43, M2 g = −0.59, M3 g = −0.68) i.e. higher training frequency (two‐ and three‐times‐per‐week versus one‐time‐per‐week) led to greater improvements once the typical plateau in performance had occurred. Hb increased in W1 and W2, while no changes were observed in Hct or HRrest. 1‐RM increased from months 1–3 in all intervention groups (except M2) and from month 4–9 only in M3 and in all women intervention groups. During follow‐up, maximal strength was maintained but cycling economy returned to the baseline values in all training groups. These data indicate that RT led to significant improvements in cardiorespiratory fitness during the initial 3 months of training. This was partly explained by the RT protocol performed but further improvements may require higher training frequency. These changes are likely to be originated by the improved cardiorespiratory functions rather than neuromuscular adaptations evidenced by a lack of significant relationship during the intervention as well as the divergent results during follow‐up.

Mechanisms underpinning protection against eccentric exercise-induced muscle damage by ischemic preconditioning

Eccentric exercise training is effective for increasing muscle mass and strength, and improving insulin sensitivity and blood lipid profiles. However, potential muscle damage symptoms such as prolonged loss of muscle function and delayed onset of muscle soreness may restrict the use of eccentric exercise, especially in clinical populations. Therefore, strategies to reduce eccentric exercise-induced muscle damage (EIMD) are necessary, and an extensive number of scientific studies have tried to identify potential intervention modalities to perform eccentric exercises without adverse effects. The present paper is based on a narrative review of current literature, and provides a novel hypothesis by which an ischemic preconditioning (IPC) of the extremities may reduce EIMD. IPC consists of an intermittent application of short-time non-lethal ischemia to an extremity (e.g. using a tourniquet) followed by reperfusion and was discovered in clinical settings in an attempt to minimize inflammatory responses induced by ischemia and ischemia-reperfusion-injury (I/R-Injury) during surgery. The present hypothesis is based on morphological and biochemical similarities in the pathophysiology of skeletal muscle damage during clinical surgery and EIMD. Even though the primary origin of stress differs between I/R-Injury and EIMD, subsequent cellular alterations characterized by an intracellular accumulation of Ca2+, an increased production of reactive oxygen species or increased apoptotic signaling are essential elements for both. Moreover, the incipient immune response appears to be similar in I/R-Injury and EIMD, which is indicated by an infiltration of leukocytes into the damaged soft-tissue. Thus far, IPC is considered as a potential intervention strategy in the area of cardiovascular or orthopedic surgery and provides significant impact on soft-tissue protection and downregulation of undesired excessive inflammation induced by I/R-Injury. Based on the known major impact of IPC on skeletal muscle physiology and immunology, the present paper aims to illustrate the potential protective effects of IPC on EIMD by discussing possible underlying mechanisms.

The repeated bout effect of traditional resistance exercises on running performance across three bouts

This study investigated the repeated bout effect of 3 typical lower body resistance-training sessions on maximal and submaximal effort running performance. Twelve resistance-untrained men (age, 24 ± 4 years; height, 1.81 ± 0.10 m; body mass, 79.3 ± 10.9 kg; peak oxygen uptake, 48.2 ± 6.5 mL·kg-1·min-1; 6-repetition maximum squat, 71.7 ± 12.2 kg) undertook 3 bouts of resistance-training sessions at 6-repetitions maximum. Countermovement jump (CMJ), lower-body range of motion (ROM), muscle soreness, and creatine kinase (CK) were examined prior to and immediately, 24 h (T24), and 48 h (T48) after each resistance-training bout. Submaximal (i.e., below anaerobic threshold (AT)) and maximal (i.e., above AT) running performances were also conducted at T24 and T48. Most indirect muscle damage markers (i.e., CMJ, ROM, and muscle soreness) and submaximal running performance were significantly improved (P < 0.05; 1.9%) following the third resistance-training bout compared with the second bout. Whilst maximal running performance was also improved following the third bout (P < 0.05; 9.8%) compared with other bouts, the measures were still reduced by 12%-20% versus baseline. However, the increase in CK was attenuated following the second bout (P < 0.05) with no further protection following the third bout (P > 0.05). In conclusion, the initial bout induced the greatest change in CK; however, at least 2 bouts were required to produce protective effects on other indirect muscle damage markers and submaximal running performance measures. This suggests that submaximal running sessions should be avoided for at least 48 h after resistance training until the third bout, although a greater recovery period may be required for maximal running sessions.

Effects of 12-Week Low or Moderate Dietary Acid Intake on Acid–Base Status and Kidney Function at Rest and during Submaximal Cycling

Prolonged effects of dietary acid intake on acid–base status and kidney function have not yet been studied in an intervention study in healthy subjects. Dietary acid load can be estimated by calculating the potential renal acid load (PRAL) of foods. Effects of low-PRAL and moderate-PRAL diets on acid–base status and kidney function were investigated during a 12-week exercise training period. Healthy, 20–50-year-old men (n = 21) and women (n = 25) participated in the study and were randomly divided into low-PRAL and moderate-PRAL groups. Before (PRE), mid-phase (MID) and after the intervention (POST), the subjects participated in measurement sessions, where a 12-h urine sample and fasting blood samples were collected, and a submaximal cycle ergometer test was performed. Net acid excretion was significantly lower after 12 weeks of the low-PRAL diet as compared to the moderate-PRAL diet, both in men and women. In low-PRAL females, capillary pH and bicarbonate were significantly higher at 75% of VO2max at POST as compared to PRE. Glomerular filtration rate decreased over the study period in moderate-PRAL men and women. The results of the present study suggest that an acidogenic diet and regularly training together may increase the acidic load of the body and start to impair the kidney function in recreationally active subjects.

Cardiorespiratory Adaptations in Elderly Men Following Different Concurrent Training Regimes

BackgroundThis study aimed to investigate the effects of different intra-session exercise orders during concurrent training (CT) on endurance performance in elderly men, as well as to verify its influence on individual responses in endurance performance.DesignTwenty-five healthy elderly men (64.7 ± 4.1 years) were placed into two groups: strength training prior to endurance training (SE, n=13), and one in the reverse order (ES, n=12). CT was performed three times a week during 12 weeks. Before and after training, peak oxygen uptake (VO2peak), maximal workload (Wmax), absolute and relative cycling economy at 25, 50, 75 and 100 W (i.e., average VO2 at different stages) were assessed.ResultsSimilar increases in VO2peak were observed in the SE and ES groups (SE: 8.1 ± 9.9%; ES: 9.3 ± 9.8%; P<0.001), as well as in Wmax (SE: 19.9 ± 19.3%; ES: 24.1 ± 24.0%; P<0.001). Moreover, significant reductions were observed in the absolute VO2 at 100 W (P<0.05) in the SE and ES groups. No difference between groups was observed. In the ES group, one subject did not respond positively in terms of both VO2max and Wmax, whereas 4 subjects did not respond positively in terms of both VO2max and Wmax in SE group.ConclusionsCT improved maximal and submaximal endurance performance in elderly men, independent of intra-session exercise order. However, it seems that the ES order elicited more individual responsiveness in terms of maximal endurance performance than SE order..

The impact of exercise-induced muscle damage on performance test outcomes in elite female basketball players

Abstract Doma, K, Leicht, A, Sinclair, W, Schumann, M, Damas, F, Burt, D, and Woods, C. Impact of exercise-induced muscle damage on performance test outcomes in elite female basketball players. J Strength Cond Res 32(6): 1731–1738, 2018—The purpose of this study was 2-fold: first, to examine the impact of exercise-induced muscle damage (EIMD) on physical fitness qualities after a basketball-specific training session; second, to determine the reproducibility of the sport-specific performance measures in elite female basketball players. Ten elite female basketball players (age 25.6 ± 4.5 years; height 1.8 ± 0.7 m; and body mass 76.7 ± 8.3 kg) undertook a 90-minute training session involving repeated jumping, sprinting, and game-simulated training. Indirect muscle damage markers (i.e., countermovement jump, delayed onset of muscle soreness [DOMS], and creatine kinase [CK]) and sport-specific performances (i.e., change-of-direction [COD] test and suicide test [ST]) were measured before and 24 hours after training. These measures were also collected 1 week after training to determine the reproducibility of the basketball-specific performance measures. A significant reduction in lower-body power (−3.5 ± 3.6%; p ⩽ 0.05), while a significant increase in DOMS (46.7 ± 26.3%; p ⩽ 0.05) and CK (57.6 ± 23.1%; p ⩽ 0.05) was observed 24 hours after exercise. The ST was also significantly increased (2.1 ± 1.8%; p ⩽ 0.05), although no difference was observed for COD (0.1 ± 2.0%; p > 0.05). The intraclass correlation coefficient and coefficient of variation for the COD and ST were 0.81 and 0.90, respectively, and 1.9 and 1.5%, respectively. In conclusion, appropriate recovery should be considered the day after basketball-specific training sessions in elite basketball players. Furthermore, this study showed the usability of performance measures to detect changes during periods of EIMD, with acceptable reproducibility and minimal measurement error.

Reliability and validity of a new accelerometer-based device for detecting physical activities and energy expenditure

Background Objective assessments of sedentary behavior and physical activity (PA) by using accelerometer-based wearable devices are ever expanding, given their importance in the global context of health maintenance. This study aimed to determine the reliability and validity of a new accelerometer-based analyzer (Fibion) for detecting different PAs and estimating energy expenditure (EE) during a simulated free-living day. Methods The study consisted of two parts: a reliability (n = 18) and a validity (n = 19) test. Reliability was assessed by a 45 min protocol of repeated sitting, standing, and walking (i.e., 3 × 15 min, repeated twice), using both Fibion and ActiGraph. Validity was assessed by a 12 h continuous sequence tasks of different types (sitting, standing, walking, and cycling) and intensities (light [LPA], moderate [MPA], and vigorous [VPA]) of PA. Two Fibion devices were worn on the thigh (FT) and in the pocket (FP), respectively and were compared with criteria measures, such as direct observation (criterion 1) and oxygen consumption by a portable gas analyzer, K4b2 (criterion 2). Results FT (intra-class correlation coefficients (ICCs): 0.687–0.806) provided similar reliability as the Actigraph (ICCs: 0.661–0.806) for EE estimation. However, the measurement error (ME) of FT compared to the actual time records indicated an underestimation of duration by 5.1 ± 1.2%, 3.8 ± 0.3% and 14.9 ± 2.6% during sitting, walking, and standing, respectively. During the validity test, FT but not FP showed a moderate agreement but lager variance with the criteria (1 and 2) in assessing duration of sitting, long sitting, LPA, MPA, and VPA (p > 0.05, ICCs: 0.071–0.537), as well as for EE estimation of standing, LPA, MPA, and VPA (p > 0.05, ICCs: 0.673–0.894). Conclusions FT provided similar reliability to that of the Actigraph. However, low correlations between subsequent measurements of both devices indicated large random MEs, which were somewhat diminished during the simulated 12 h real-life test. Furthermore, FT may accurately determine the types, intensities of PA and EE during prolonged periods with substantial changes in postures, indicating that the location of the accelerometer is essential. Further study with a large cohort is needed to confirm the usability of Fibion, especially for detecting the low-intensity PAs.

Anatomical versus functional motor points of selected upper body muscles

In this study we aimed to identify nerve entry points (NEPs) of superficial skeletal muscles obtained by dissection of 20 human cadavers and compared them with motor points (MP) obtained previously by electrical stimulation.

Ischemic Preconditioning Blunts Muscle Damage Responses Induced by Eccentric Exercise

Purpose Ischemic preconditioning (IPC) is known to reduce muscle damage induced by ischemia and reperfusion injury during surgery. Because of similarities between the pathophysiological formation of ischemia and reperfusion injury and eccentric exercise–induced muscle damage (EIMD), as characterized by an intracellular accumulation of Ca2+, an increased production of reactive oxygen species, and increased proinflammatory signaling, the purpose of the present study was to investigate whether IPC performed before eccentric exercise may also protect against EIMD. Methods Nineteen healthy men were matched to an eccentric-only (ECC; n = 9) or eccentric proceeded by IPC group (IPC + ECC; n = 10). The exercise protocol consisted of bilateral biceps curls (3 × 10 repetitions at 80% of the concentric one-repetition maximum). In IPC + ECC, IPC was applied bilaterally at the upper arms by a tourniquet (200 mm Hg) immediately before the exercise (3 × 5 min of occlusion, separated by 5 min of reperfusion). Creatine kinase (CK), arm circumference, subjective pain (visual analog scale score), and radial displacement (tensiomyography, maximal radial displacement) were assessed before IPC, preexercise, postexercise, and 20 min, 2 h, 24 h, 48 h, and 72 h postexercise. Results CK differed from baseline only in ECC at 48 h (P < 0.001) and 72 h (P < 0.001) postexercise. After 24, 48, and 72 h, CK was increased in ECC compared with IPC + ECC (between groups: 24 h, P = 0.004; 48 h, P < 0.001; 72 h, P < 0.001). The visual analog scale score was significantly higher in ECC at 24–72 h postexercise when compared with IPC + ECC (between groups: all P values < 0.001). The maximal radial displacement was decreased on all postexercise days in ECC (all P values < 0.001) but remained statistically unchanged in IPC + ECC (between groups: P < 0.01). Conclusions These findings indicate that IPC performed before a bout of eccentric exercise of the elbow flexors blunts EIMD and exercise-induced pain while maintaining the contractile properties of the muscle.