Effects of knee extension with different speeds of movement on muscle and cerebral oxygenation

Background

One of the mechanisms responsible for enhancing muscular hypertrophy is the high metabolic stress associated with a reduced muscular oxygenation occurring during exercise, which can be achieved by reducing the speed of movement. Studies have tested that lowered muscle oxygenation artificially induced by an inflatable cuff, could provoke changes in prefrontal cortex oxygenation, hence, to central fatigue. It was hypothesized that (1) exercising with a slow speed of movement would result in greater increase in cerebral and greater decrease in muscle oxygenation compared with exercises of faster speed and (2) the amount of oxygenation increase in the ipsilateral prefrontal cortex would be lower than the contralateral one.

Methods

An ISS Imagent frequency domain near infrared spectroscopy (NIRS) system was used to quantify oxygenation changes in the vastus lateralis muscle and prefrontal cortex (contra- and ipsilateral) during unilateral resistance exercises with different speeds of movement to voluntary fatigue. After one maximal repetition (1RM) test, eight subjects performed three sets of unilateral knee extensions (∼50% of 1RM), separated by 2 min rest periods, following the pace of 1 s, 3 s and 5 s for both concentric and eccentric phases, in a random order, during separate sessions. The amount of change for NIRS parameters for muscle (ΔHb: deoxyhemoglobin, ΔHbO: oxyhemoglobin, ΔHbT: total hemoglobin, ΔStO₂: oxygen saturation) were quantified and compared between conditions and sets by two-way ANOVA RM. Differences in NIRS parameters between contra- and ipsilateral (lobe) prefrontal cortex and conditions were tested.

Results

Exercising with slow speed of movement was associated to larger muscle deoxygenation than normal speed of movement, as revealed by significant interaction (set × condition) for ΔHb (p = 0.01), and by significant main effects of condition for ΔHbO (p = 0.007) and ΔStO₂ (p = 0.016). With regards to the prefrontal cortex, contralateral lobe showed larger oxygenation increase than the ipsilateral one for ΔHb, ΔHbO, ΔHbT, ΔStO₂ in each set (main effect of lobe: p < 0.05). Main effects of condition were significant only in set1 for all the parameters, and significant interaction lobe × condition was found only for ΔHb in set1 (p < 0.05).

Discussion

These findings provided evidence that speed of movement influences the amount of muscle oxygenation. Since the lack of oxygen in muscle is associated to increased metabolic stress, manipulating the speed of movement may be useful in planning resistance-training programs. Moreover, consistent oxygenation increases in both right and left prefrontal lobes were found, suggesting a complementary interaction between the ipsi- and contralateral prefrontal cortex, which also seems related to fatigue.

Field-based physical performance of elite and sub-elite middle-adolescent soccer players

The aim of the current study was to evaluate field-based physical performance of under 16 years (U16) elite and sub-elite soccer players. Forty elite (n = 20) and sub-elite (n = 20) soccer players were enrolled and tested for countermovement jump (CMJ), 10-m sprint and agility, in terms of sprint with 90° turns (S90), S90 with ball, Slalom, Slalom with ball, and reactive agility (RAT). Statistical and practical significant differences were observed in CMJ, S90 and RAT between elite and sub-elite. Elite players exhibited a likely better performance in Slalom, Slalom with ball and S90 with ball despite a non-significant difference by level of play. Concerning sprint ability, both groups showed similar performance in the 10-m sprint. Countermovement jump and agility tests are field-based physical assessments recommended to better distinguish between U16 elite and sub-elite soccer players.

Effects of traditional balance and slackline training on physical performance and perceived enjoyment in young soccer players

The aim of this study was to evaluate the effects of 12-week balance and slackline training programs on physical performance and perceived enjoyment scale in young soccer players. Forty-one preadolescent soccer players were assigned to two experimental groups performing traditional balance (BLT) or slackline training (SLT), and a control group. Pre-post assessment encompassed Balance Error Scoring System (BESS), Star Excursion Balance test (SEBT), sprint with 90° turns (S90), and countermovement jump (CMJ). The rate of perceived enjoyment scale (PACES) was applied at the end of the experimental period. SLT and BLT improved similarly in BESS, SEBT and S90. No changes were detected in the CMJ. Regarding PACES score, SLT presented significantly higher values than BLT. Young athletes may benefit from a motivating training approach, thus, a designed program based on slackline drills should be preferable to improve physical performance in terms of balance and change of direction ability in preadolescent soccer players.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

Physical Performance Comparison between Under 15 Elite and Sub-Elite Soccer Players

The aim of this study was to compare the physical performance profile among young soccer players of different competitive levels. Two teams of elite (n = 22) and sub-elite (n = 22) soccer players at national (highly skilled) and regional (moderately skilled) level were recruited in the study. All participants were tested using a modified Illinois change of direction speed test, a T-drill with and without a ball, a countermovement jump, and a 10-m sprint. The analysis revealed significant differences in favor of elite players in sprint (d = 1.54, large) and vertical jump (d = 2.03, very large) outcomes, while no differences were observed in both modified Illinois change of direction speed (d = 0.16, trivial) and T-drill (d = 0.20, small) tests between the groups. The ability to change direction and speed with and without a ball was found not to be suitable enough to highlight the difference among youth players with moderate-to-high level of play. In conclusion, multi-testing approach based on task-related power should include vertical jump and sprint performance to delineate players of a higher level.

Individualized dry-land intervention program for an elite Paralympic swimmer

The aim of this retrospective case study is the longitudinal description of the physical and functional parameters of a top-level Paralympic swimmer class S9-SB8-SM9 during four swimming seasons of training, from the Paralympic games in London 2012 to the Paralympic games in Rio 2016. A 22-year-old male swimmer underwent a specific preventive dry-land training based on diaphragmatic breathing, postural alignment, and slow-velocity resistance training aimed to improve his muscle strength. He was tested by using the Functional Movement Screen™, photographic postural assessment and vertical jump. The swimmer improved his functional, postural and strength parameters indicating a better functional movement and muscular power. These results show that a four-year specific dry-land intervention could be capable of enhancing the functional and physical requirements of a top-level Paralympic swimmer. This approach might be a suitable novel alternative for coaches and athletic trainers to integrate their training protocols for athletes with similar impairments.

Bilateral asymmetry of skin temperature is not related to bilateral asymmetry of crank torque during an incremental cycling exercise to exhaustion

Although moderate relationships (|r| ∼ 0.5) were reported between skin temperature and performance-related variables (e.g., kinetic), it remains unclear whether skin temperature asymmetry reflects muscle force imbalance in cycling. Therefore, the aim of this study was to assess whether a relationship exists between kinetic and thermal asymmetry during a fatiguing exercise. Ten elite cyclists were enrolled and tested on a maximal incremental cycling test. Peak crank torques of both legs were obtained at the initial and final workload. Likewise, bilateral skin temperatures were recorded before and after exercise. Asymmetric indexes were also calculated for kinetic (AIK) and skin temperature (AIT) outcomes. The bilateral peak crank torques showed a larger difference at the final compared to the initial workload (p < 0.05) of the incremental exercise. Conversely, the bilateral skin temperature did not show any differences at both initial and final workload (p > 0.05). Additionally, trivial relationships were reported between AIK and AIT (-0.3 < r < 0.2) at the initial and final workload. The obtained results showed that changes in bilateral kinetic values did not reflect concurrent changes in bilateral skin temperatures. This finding emphasizes the difficulty of associating the asymmetry of skin temperature with those of muscle effort in elite cyclists. Lastly, our study also provided further insights on thermal skin responses during exhaustive cycling exercise in very highly-trained athletes.

Complexity, adaptations and variations in the secondary insemination system of female Dermanyssina mites (Acari: Anactinothrichida: Gamasida): the case of Afrocypholaelaps africana

Gamasine mites, mainly of the taxon Dermanyssina, possess a secondarily evolved insemination system (sperm access system), of which there are two, generally recognized, structurally different types, the laelapid- and the phytoseiid-type. The ultrastructure of the female sperm access system in Afrocypholaelaps africana is described. It consists of paired insemination pores, opening between the bases of legs three and four, and paired cuticle-lined tubules that converge into a large, sack-like spermatheca, remarkably cuticle-lined as well. The entire spermatheca and part of the tubules are embedded in a peculiar syncytial tissue where numerous sperm cells are present. The general organization of this insemination system is of the laelapid-type. However, it presents striking structural differences, compared with the systems described in Varroa destructor and Hattena cometis, the other gamasine mites having a laelapid-type system studied ultrastructurally until now. The functional morphology, complexity and variations of the sperm access system in Dermanyssina are discussed and correlated with the evolutionary biology of the group.

Thermography for skin temperature evaluation during dynamic exercise: a case study on an incremental maximal test in elite male cyclists

The use of thermal imaging in monitoring the dynamic of skin temperature during prolonged physical exercise is central to assess athletes' ability to dissipate heat from the skin surface to the environment. In this study, seven elite cyclists completed an incremental maximal cycling test to evaluate their skin temperature response under controlled-environment conditions. Thermal images have been analyzed using a method based on maxima detection (T_max). Data confirmed a reduction in skin temperature due to vasoconstriction during the exercise, followed by a temperature increment after exhaustion. A characteristic hot-spotted thermal pattern was found over the skin surface in all subjects. This research confirmed also the notable ability by highly trained cyclists to modify skin temperature during an incremental muscular effort. This study gives additional contributions for understanding the capability of the T_max method applied to the thermoregulatory physiological processes.

Acute effects of kinesio taping on a 6 s maximal cycling sprint performance

Based on the hypothesis that tactile stimulation affects muscle activation levels, we theorized that taping vastus medialis and vastus lateralis muscles would improve a 6 s sprint cycling performance. Thus, the aim of this study was to determine whether the use of kinesio taping (KT) was helpful in increasing maximal-intensity cycling exercise. Sixteen active healthy subjects were enrolled in a randomized placebo, repeated measures design. All subjects were tested on a cycle ergometer under three conditions: without taping, taping along anterior thigh muscles and sham taping across the same muscle groups. Results showed a significant increase in peak power output and total work after the application compared to the condition with no tape applied (p < 0.05). No significant difference was found between the two modes of application. Our findings indicated that the tactile stimulation of KT applied longitudinally provided positive effects during a sprint cycling performance in healthy and active subjects.

Comparison between continuous and discontinuous incremental treadmill test to assess velocity at V̇O2max

BACKGROUND

The velocity associated with maximum aerobic power (vV̇O2max) is an important physiological parameter, which is utilized to determine relative workloads on the field. The testing modality adopted to evaluate it, though, may cause differences in vV̇O2max assessment and, in turn, in training intensity. The aim of the study was to compare two different testing modalities (continuous incremental ramp and discontinuous square wave (SW) protocols) for vV̇O2max assessment on the treadmill.

METHODS

Seventeen physically active participants performed three maximum incremental tests on a treadmill: two continuous ramp protocols, with different ramp slopes (R1, 1 km/h every minute; and R2, 1 km/h every 2 minutes), and one discontinuous SW protocol, in random order, for maximum oxygen uptake (V̇O2max) and vV̇O2max determination. Cardiorespiratory and metabolic parameters were collected breath-by-breath at rest and during exercise.

RESULTS

vV̇O2max was significantly higher in R1 and R2 compared to SW (20.7±0.5, 18.6±0.4, 16.8±0.6 km/h for R1, R2, and SW, respectively; P<0.001). No significant differences were found among protocols for V̇O2max (56.7±1.1, 57.0±1.2, and 56.6±1.2 mL/min/kg for SW, R1, R2, respectively) as well as for expiratory ventilation, carbon dioxide production, blood lactate concentration, and heart rate.

CONCLUSIONS

In spite of similar V̇O2max values, vV̇O2max was higher during continuous incremental ramp tests compared to SW possibly due to the longer time for cardiorespiratory and metabolic adjustments, suggesting different aerobic and anaerobic metabolism involvement. The differences among protocols should be considered when vV̇O2max is used for training purposes.

Peripheral neuromuscular fatigue induced by repeated-sprint exercise: cycling vs. running

BACKGROUND

Peripheral fatigue in knee extensor (KE) and plantar flexor (PF) muscles were investigated following repeated-sprint ability (RSA) cycling and running tests.

METHODS

Both RSA tests involved 5x6 s sprints and peripheral fatigue was quantified using diverse electrical stimulations (1Hz, 10Hz, 20Hz, 50Hz and 100Hz).

RESULTS

RSA cycling induced higher KE decrements in peak torque (PT), maximal rate of torque development and relaxation (PT decrements at different stimulation frequencies: from -39% to -53% cycling vs. -16% to -39% running, P<0.049). The PT ratios of the KE did not highlight differences in low-frequency fatigue. No major differences were noted in PT decrements of PF (P>0.231); however, greater reductions in some PT ratios (10/100 Hz, 20/50 Hz and 20/100 Hz) confirmed the presence of low-frequency fatigue in PF following RSA cycling. Subjects reported significantly higher RPE leg values following RSA cycling (8.2 vs 7.3 respectively, P=0.018) despite no differences in blood lactate, hydrogen ions and bicarbonates (P>0.467).

CONCLUSIONS

Higher levels of peripheral fatigue induced by RSA cycling may be partially related to longer fractional duration of muscle contraction phases that can limit local blood flow. The discrepancies in neuromuscular fatigue between KE and PF can be explained by differences in muscle fibre composition or muscle contributions during RSA tests.

Jump Rope Training: Balance and Motor Coordination in Preadolescent Soccer Players

General physical practice and multidimensional exercises are essential elements that allow young athletes to enhance their coordinative traits, balance, and strength and power levels, which are linked to the learning soccer-specific skills. Jumping rope is a widely-used and non-specific practical method for the development of athletic conditioning, balance and coordination in several disciplines. Thus, the aim of this study was to investigate the effects of a short-term training protocol including jumping rope (JR) exercises on motor abilities and body balance in young soccer players. Twenty-four preadolescent soccer players were recruited and placed in two different groups. In the Experimental group (EG), children performed JR training at the beginning of the training session. The control group (CG), executed soccer specific drills. Harre circuit test (HCT) and Lower Quarter Y balance test (YBT-LQ) were selected to evaluate participant's motor ability (e.g. ability to perform rapidly a course with different physical tasks such as somersault and passages above/below obstacles ) and to assess unilateral dynamic lower limb balance after 8 weeks of training. Statistical analysis consisted of paired t-test and mixed analysis of variance scores to determine any significant interactions. Children who performed jumping rope exercises showed a significant decrease of 9% (p < 0.01, ES = 0.50-0.80) in the performance time of HCT. With regard to the CG, no differences were highlighted (p > 0.05, ES = 0.05-0.2) from pre- to post-training. A training-by-group interaction was found for the composite score in both legs (p < 0.05, Part η(2) > 0.14). Our findings demonstrated that JR practice within regular soccer training enhanced general motor coordination and balance in preadolescent soccer players. Therefore, the inclusion of JR practice within regular soccer training session should encouraged to improve children's motor skills. Key pointsPerforming jumping rope exercises within a regular soccer program can be an additional method to improve balance and motor coordination.The performance improvement in the Harre Circuit Test associated with jump rope training can potentially be attributed to an enhancement of the inter-limb coordination and SSC ability.Results from the present study indicate that young soccer players should be encouraged to practice general physical activities together with sport-specific exercise during their training sessions.

Ultrastructural and functional adaptations of the female reproductive system in the family Heterozerconidae (Acari, Anactinotrichida, Gamasida, Heterozerconina) and implications for the systematic position of the group

Heterozerconidae is a poorly known, early derived mite family belonging to Heterozerconina (Monogynaspida, Gamasida (= Mesostigmata)). The systematic position of the family is still controversial and little is known about the biology and anatomy of the taxon. In this paper, the gross anatomy, ultrastructure and functional morphology of the female reproductive system are described comparing genera from different geographic areas. The occurence of podospermy (i.e. the use of a sperm transfer process carried by the fixed digit of the male chelicerae to inseminate females through secondary insemination pores instead of through the oviporus) as insemination mode in this family was documented. Nevertheless, morphological and functional evidence in the reproductive system of the females supports the idea that, in the same family, more than one insemination mode is present: some genera are plesiomorphically tocospemic (i.e. insemination through the oviporus) while others switched to podospermy. Such discovery is of fundamental importance for the determination of the relationship between the family Heterozerconidae and the family Discozerconidae, both belonging tentatively to Heterozerconina and for the phylogenetic position of the Heterozerconina among Gamasida.

Effects of different core exercises on respiratory parameters and abdominal strength

[Purpose] This study determined the effects a new modality of core stabilization exercises based on diaphragmatic breathing on pulmonary function, abdominal fitness, and movement efficiency. [Subjects] Thirty-two physically active, healthy males were randomly assigned to an experimental group (n = 16) and a control group (n = 16). [Methods] The experimental group combined diaphragmatic breathing exercises with global stretching postures, and the control group performed common abdominal exercises (e.g., crunch, plank, sit-up), both for 15 minutes twice weekly for 6 weeks. Pulmonary function (measured by forced vital capacity, forced expiratory volume in 1 second, and peak expiratory flow) and abdominal fitness (measured with the American College of Sports Medicine curl-up [cadence] test and the Functional Movement Screen(TM)) were evaluated before and after the intervention. [Results] Significant changes in curl-up (cadence) test scores, Functional Movement Screen scores, and all pulmonary parameters were recorded in the experimental group at the posttraining assessment, whereas in the control group, no significant differences over baseline were observed in any parameters. [Conclusion] Compared with traditional abdominal exercises, core stabilization exercises based on breathing and global stretching postures are more effective in improving pulmonary function and abdominal fitness.

Reliability of the assessment of peripheral muscle fatigue induced by high-intensity intermittent exercise

AIM

Reliability of the assessment of peripheral fatigue induced in knee extensors by high-intensity intermittent running exercise (HIE) was established in ten amateur soccer players (age: 18±1, height: 178±5 cm, weight: 68±8 kg).

METHODS

Transcutaneous electrical stimulations before and after HIE determined muscle contractile properties on three separate occasions (T1, T2 and T3), each separated by 7 days.

RESULTS

No significant differences were noted for any of the parameters measured (P=0.101). The ICC values for peak torque (PT) varied from moderate to high, with the exception of PT at 10-Hz calculated comparing T2 vs. T1 (range PRE=0.78-0.92; POST=0.76-0.97). The ICC derived from PT percentage decrements data were all low, with the exception of PT decrements at 1 Hz calculated comparing T3 vs. T2 (ICC=0.85, moderate). The TE for all contractile parameters obtained using 1-Hz and 100-Hz electrical stimulations were below 10%, including some that demonstrated a TE lower than 5%. Muscle contractile properties determined using 10-Hz stimulations showed a higher level of TE (range: 3.2-15.1%). Similar results were obtained for maximal rate of torque development and torque relaxation.

CONCLUSION

From the results of this study it can be concluded that muscle contractile properties express a good level of reliability in baseline and postexercise measures following familiarization.

The efficacy of Italian guidelines in promoting oral health in children and adolescents

AIM

The purpose of the study was to evaluate the efficacy of the guidelines on oral health published by the Italian Health Ministry.

STUDY DESIGN

1239 patients (582 girls and 657 boys) with a mean age of 4.46 (SD 2.81) years were evaluated before application of the guidelines by paediatricians (T0) for the presence of caries, gingivitis, diseases of the oral mucosa, and malocclusion. Only patients aged 6 months, 3 years, 6 years, and 9 years at T0 were taken into consideration. All patients were reevaluated after application of the ministerial guidelines (T1).

METHODS

the study took place over a 3-year period. Enrolled patients referred to the outpatient clinics of three paediatricians of the Province of Genoa who strictly applied the ministerial guidelines.

STATISTICS

Chi square test analysis was performed to evaluate a statistically significant decrease in the incidence of caries, gingivitis and diseases of the oral mucosa.

RESULTS

After a 3-year follow-up collected data underlined a statistically significant decrease in the incidence of dental caries, gingivitis and oral mucosal diseases after implementation of the recommended ministerial guidelines. A statistically significant decrease of malocclusions was also evident in the elder patients (12 years old at T1).

CONCLUSION

The accurate implementation of the Guidelines is supported. Only collaboration and increased synergy between paedodontists and paediatricians can fulfill the objectives which were the reason for publishing the "National guidelines for the promotion of oral health and the prevention of oral diseases in developmental age".

Self-Reported Knee Symptoms Assessed by KOOS Questionnaire in Downhill Runners (Skyrunners)

BACKGROUND

The knee is the weight-bearing joint most commonly associated with sports injuries, and therefore is most at risk of developing degenerative changes, including osteoarthritis. Skyrunners can be considered to be at risk of developing symptoms of post-traumatic osteoarthritis due to downhill running.

AIM

The aim of this study was to analyze the health of the knee joints of a large group of these athletes via a specific self-report questionnaire.

METHODS

This study was carried out by asking the participants of seven official Skyraces (22.4±3.1 km length; 1596±393 m elevation) to fill out a questionnaire. Information regarding age, sex, downhill elevation (m) during training and competitions over the last month, and history of previous knee injury was also collected before the participants filled out the Knee injury and Osteoarthritis Outcome Score (KOOS), which is a reliable and validated instrument designed to assess patients' opinions about their knees and associated problems that can result in post-traumatic osteoarthritis. Athletes were divided into six age groups (from 17 to 70 years) and 12 groups based on the downhill gradient they had covered over the last month (from 1,000 to 40,000 m).

RESULTS

Six hundred twenty-one questionnaires were collected from 45% of the participants in the seven races. Multivariate analysis revealed that self-reported KOOS scores were unrelated to age, sex and monthly downhill gradient. Only 74 (12%) of the participants reported previous knee injuries. Significant differences in the five subscales of the KOOS were found between skyrunners with and without previous knee injuries (P<0.01).

CONCLUSIONS

In the studied population, regular training for downhill running and participation in Skyraces could not be considered risk factors for subjective knee symptoms. Skyrunners with self-reported histories of knee injuries scored worse on all five subscales of the KOOS.