Felipe Pivetta Carpes

Effects of a program for trunk strength and stability on pain, low back and pelvis kinematics, and body balance: A pilot study

The purpose of this pilot study was to investigate the effects of trunk strength and stability training on body balance and low back and pelvis kinematics during gait in females. Six subjects volunteered to do 20 sessions of training. Data collection involved a qualitative pain grade test, low back stabilization tests, low back and pelvis kinematics, and body balance assessment. Results indicate the absence or decrease in the low back pain, and also an increase in the stabilization and strength of low back and pelvis complex. The 3-D kinematics showed statistically significant differences (p<0.05) when compared pre- to post-training. The body balance was improved as well as the range of motion (ROM) was improved for trunk rotation, pelvis inclination and low back flexion. The results suggest the influence of trunk strength and stability on low back and pelvis pain and kinematics as well as on body balance. Further studies with a larger sample and/or a control group must be conducted in an attempt to confirm this hypothesis.

Lower extremity kinematic asymmetry in male and female athletes performing jump-landing tasks

OBJECTIVES Higher side-to-side asymmetry among female athletes compared to their male counterparts during bilateral athletic tasks such as landing from a jump has been proposed as a potential source of non contact knee injuries. However, the kinematic symmetry and potential sex differences during the initial (and most dangerous) phase of bilateral landings have not been examined. The objective of this project is to evaluate lower extremity kinematic asymmetry among recreational athletes during forward jump landing and drop landing tasks. DESIGN Repeated measures laboratory experiment. METHODS Thirteen male and 15 female athletes performed landing tasks on a force plate while kinematic data were collected. Kinematic asymmetry between legs was calculated for the initial phase of landing for lower extremity kinematics. ANOVA tests and effect size calculations were used to measure the effect of sex, landing task and their interaction on kinematic asymmetry. RESULTS Athletes exhibited higher asymmetry for knee valgus (d=0.5, p=0.006) and hip adduction (d=0.5, p=0.057) when performing forward compared to drop landings. Females landed with greater knee valgus asymmetry than males during forward landings (d=0.7, p=0.078) and with greater ankle abduction asymmetry during drop landings (d=0.5, 0.091). CONCLUSIONS Female athletes exhibited greater frontal plane knee and ankle kinematic asymmetry than males during forward landings which may be related to the higher rate of ACL injury. Forward landings elicited greater hip adduction and knee valgus asymmetries than drop landings and, therefore it may be more appropriate for field testing when screening for asymmetries.

Effect of low back pain on postural stability in younger women: Influence of visual deprivation

SUMMARY This study investigated the effect of low back pain (LBP) on body balance during normal and visual deprivation during standing in a LBP group (10 women) and a control group (10 women). A 3-D force plate was used to measure the center of pressure (COP) anteroposterior and mediolateral displacements, and resultant velocity. ANOVA was used to compare situations. LPB group presented higher amplitudes of COP for anterioposterior direction (p<0.01) in conditions of open (3.07 ± 0.53 cm) and closed eyes (3.70 ± 0.71 cm) than healthy women (1.39 ± 0.17 cm and 1.75 ± 0.36 cm, for open and closed eyes, respectively). Similar results were found for COP involving mediolateralsway. The resultant COP velocity was larger for LBP group (p<0.05) when visual information was removed (3.03 ± 0.68 m/s and 3.63 ± 1.33 m/s for LBP and healthy women, respectively). LBP influenced the stability of young women during quiet standing, and the visual deprivation appears to reinforce LBP effects.

Cadence and Workload Effects on Pedaling Technique of Well-Trained Cyclists

This study investigated the effects of changing cadence and workload on pedaling technique. Eight cyclists were evaluated during an incremental maximal cycling and two 30-minute submaximal trials at 60% and 80% of maximal power output (W(60%) and W(80%), respectively). During submaximal 30-minute trials, they cycled for 10 minutes at a freely chosen cadence (FCC), 10 minutes at a cadence 20% above FCC (FCC+20%), and 10 minutes at a cadence 20% below FCC (FCC-20%). Pedal forces and kinematics were evaluated. The resultant force (RF), effective force (EF), index of effectiveness (IE) and IE during propulsive and recovery phase (IEprop and IErec, respectively) were computed. For W(60%), FCC-20% and FCC presented higher EFmean (69+/-9 N and 66+/-14 N, respectively) than FCC+20% (52+/-14 N). FCC presented the highest IEprop (81+/-4%) among the cadences (74+/-4 and 78+/-5% for FCC-20% and FCC+20%, respectively). For W(80%), FCC presented higher EFmean (81+/-5 N) than FCC+20% (72 +/- 10 N). The FCC-20% presented the lower IEprop (71+/-7%) among the cadences. The EFmin was higher for W(80%) than W(60%) for all cadences. The IE was higher at W (80%) (61+/-5%) than W (60%) (54+/-9%) for FCC+20% (all p<0.05). Lower cadences were more effective during the recovery phase for both intensities and FCC was the best technique during the propulsive phase.

Relationship between skin temperature and muscle activation during incremental cycle exercise.

While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<-0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test.

Influence of leg preference on bilateral muscle activation during cycling

Abstract The purpose of this study was to investigate asymmetry of muscle activation in participants with different levels of experience and performance with cycling. Two separate experiments were conducted, one with nine cyclists and one with nine non-cyclists. The experiments involved incremental maximal and sub-maximal constant load cycling tests. Bilateral surface electromyography (EMG) and gross and net muscle efficiency were assessed. Analyses of variance in mixed linear models and t-tests were conducted. The cyclists in Experiment 1 presented higher gross efficiency (P < 0.05), whereas net efficiency did not differ between the two experiments (21.3 ± 1.4% and 19.8 ± 1.0% for cyclists and non-cyclists, respectively). The electrical muscle activity increased significantly with exercise intensity regardless of leg preference in both experiments. The coefficient of variation of EMG indicated main effects of leg in both experiments. The non-preferred leg of non-cyclists (Experiment 2) presented statistically higher variability of muscle activity in the gastrocnemius medialis and vastus lateralis. Our findings suggest similar electrical muscle activity between legs in both cyclists and non-cyclists regardless of exercise intensity. However, EMG variability was asymmetric and appears to be strongly influenced by exercise intensity for cyclists and non-cyclists, especially during sub-maximal intensity. Neural factors per se do not seem to fully explain previous reports of pedalling asymmetries.

Response inhibition during avoidance of virtual obstacles while walking

While walking, one often has to suppress and adjust a planned step in order to avoid a fall. Given that steps are preprogrammed this requires some form of motor inhibition. Motor inhibition is commonly tested in hand function and only recently attempts have been made to evaluate inhibition in the lower limbs, during step initiation. As adequate motor inhibition might play a role in avoiding falls a test to assess response inhibition during walking would be valuable. We developed a task in which subjects walked on a treadmill by stepping on projected patches of light, which could suddenly change color forcing the subjects to avoid it by shortening or lengthening their steps. The difficulty level was manipulated in 4 conditions by changing the distance available to respond. We hypothesized that larger demands on motor inhibition during walking would produce more failures and tested the performance of young adults (n=12) in order to establish the protocol for use in older adults. The failure rate on the walking test was analyzed. Reducing the available response distance by 150 mm from the easiest condition resulted in a significant increase in failure rates from 15.6% to 65.1%. Therefore, results indicate this novel test can be used to assess the level of motor inhibition during walking. Additionally, in comparison to previous literature on obstacle avoidance, our experiment shows that changing a precise aiming movement is considerably more challenging than changing the same movement executed automatically.

Memory deficits and oxidative stress in cerebral ischemia–reperfusion: Neuroprotective role of physical exercise and green tea supplementation

Ischemic stroke is a major cause of morbidity and mortality all over the world. Among impairments observed in survivors there is a significant cognitive learning and memory deficit. Neuroprotective strategies are being investigated to minimize such deficits after an ischemia event. Here we investigated the neuroprotective potential of physical exercise and green tea in an animal model of ischemia-reperfusion. Eighty male rats were divided in 8 groups and submitted to either transient brain ischemia-reperfusion or a sham surgery after 8 weeks of physical exercise and/or green tea supplementation. Ischemia-reperfusion was performed by bilateral occlusion of the common carotid arteries during 30 min. Later, their memory was evaluated in an aversive and in a non-aversive task, and hippocampus and prefrontal cortex were removed for biochemical analyses of possible oxidative stress effects. Ischemia-reperfusion impaired learning and memory. Reactive oxygen species were increased in the hippocampus and prefrontal cortex. Eight weeks of physical exercise and/or green tea supplementation before the ischemia-reperfusion event showed a neuroprotective effect; both treatments in separate or together reduced the cognitive deficits and were able to maintain the functional levels of antioxidant enzymes and glutathione.

Cycling with noncircular chainring system changes the three-dimensional kinematics of the lower limbs

This study investigated the three-dimensional (3-D) pedaling kinematics using a noncircular chainring system and a conventional system. Five cyclists pedaled at their preferred cadence at a workload of 300 W using two crank systems. Flexion/extension of the hip, knee and ankle as well as shank rotation, foot adduction/abduction, and pedal angle were measured. Joint range of motion (ROM) and angular displacements were compared between the systems. Sagittal plane ROM was significantly greater (P < 0.05) at the hip (noncircular system = 39 ± 3°; conventional system = 34 ± 4°) the knee (noncircular system = 69 ± 4°; conventional system = 57 ± 10°), and ankle (noncircular system = 21 ± 2°; conventional system = 19 ± 4°) resulting in greater pedal ROM (noncircular system = 43 ± 3°; conventional system = 37 ± 5°) while using the noncircular system. Shank rotation ROM was significantly lower (P < 0.05) while using the noncircular chainring (noncircular system = 10 ± 1°; conventional system = 14 ± 1°). These results support a significant effect of the noncircular chainring system on pedaling kinematics during submaximal exercise.

Effects of green tea and physical exercise on memory impairments associated with aging.

We investigated the effects of physical exercise and green tea supplementation (associated or not) on biochemical and behavioral parameters in the time course of normal aging. Male Wistar rats aged 9 months were divided into groups: control, physical exercise (treadmill running), and supplemented with green tea while either performing physical exercise or not. A young control group was also studied. Physical exercise and green tea supplementation lasted 3 months. Afterwards, behavioral and biochemical tests were performed. Biochemical measurements revealed differences in antioxidant and oxidant responses in hippocampus, prefrontal cortex and striatum. Behavioral testing showed age-related memory impairments reversed by physical exercise. The association of green tea supplementation and physical exercise did not provide aged rats with additional improvements in memory or brain oxidative markers. Green tea per se significantly decreased reactive oxygen species levels and improved antioxidant defenses although it did not reverse memory deficits associated with normal aging.