Increased central facilitation of antagonist reciprocal inhibition at the onset of dorsiflexion following explosive strength training

2008 ◽  
Vol 105 (3) ◽  
pp. 915-922 ◽  
Author(s):  
Svend S. Geertsen ◽  
Jesper Lundbye-Jensen ◽  
Jens B. Nielsen
Keyword(s):  
Strength Training ◽  
Human Subjects ◽  
Reciprocal Inhibition ◽  
Plantar Flexors ◽  
Healthy Human ◽  
Explosive Strength ◽  
Descending Facilitation ◽  
Antagonist Muscles ◽  
Efficient Suppression ◽  
Ankle Dorsiflexor

At the onset of dorsiflexion disynaptic reciprocal inhibition (DRI) of soleus motoneurons is increased to prevent activation of the antagonistic plantar flexors. This is caused by descending facilitation of transmission in the DRI pathway. Because the risk of eliciting stretch reflexes in the ankle plantar flexors at the onset of dorsiflexion is larger the quicker the movement, it was hypothesized that DRI may be increased when subjects are trained to perform dorsiflexion movements as quickly as possible For this purpose, 14 healthy human subjects participated in explosive strength training of the ankle dorsiflexor muscles 3 times a week for 4 wk. Test sessions were conducted before, shortly after, and 2 wk after the training period. The rate of torque development measured at 30, 50, 100, and 200 ms after onset of voluntary explosive isometric dorsiflexion increased by 24–33% ( P < 0.05). DRI was measured as the depression of the soleus H reflex following conditioning stimulation of the peroneal nerve (1.1 × motor threshold) at an interval of 2–3 ms. At the onset of dorsiflexion the amount of DRI measured relative to DRI at rest increased significantly from 6% before the training to 22% after the training ( P < 0.05). We speculate that DRI at the onset of movement may be increased in healthy subjects following explosive strength training to ensure efficient suppression of the antagonist muscles as the dorsiflexion movement becomes faster.

Spinal reciprocal inhibition in human locomotion

2004 ◽  
Vol 96 (5) ◽  
pp. 1969-1977 ◽  
Author(s):  
Aiko Kido ◽  
Naofumi Tanaka ◽  
Richard B. Stein
Keyword(s):  
Nerve Stimulation ◽  
Tibial Nerve ◽  
Human Subjects ◽  
Tibialis Anterior Muscle ◽  
Reciprocal Inhibition ◽  
Emg Activity ◽  
Healthy Human ◽  
Fast Walking ◽  
Tibial Nerve Stimulation ◽  
The Difference

The purpose of this paper was to study spinal inhibition during several different motor tasks in healthy human subjects. The short-latency, reciprocal inhibitory pathways from the common peroneal (CP) nerve to the soleus muscle and from the tibial nerve to the tibialis anterior muscle were studied as a depression of ongoing voluntary electromyograph (EMG) activity. First, the effect of stimulus intensity on the amount of inhibition was examined to decide an appropriate stimulation to study the task-dependent modulation of inhibition. Then, the inhibition at one level of stimulation (1.5 × motor threshold) was investigated during standing, walking, and running. The change in slope of inhibition vs. EMG level, which approximates the fraction of ongoing activity that is inhibited, decreased with CP stimulation from 0.52 during standing to 0.30 during fast walking (6 km/h) to 0.17 during running at 9 km/h. Similarly, the slope decreased with tibial nerve stimulation from 0.68 (standing) to 0.42 (fast walking) to 0.35 (running at 9 km/h). All differences, except the last one, were highly significant ( P < 0.01, Student's t-test). However, the difference between walking (0.42) and running (0.36) at the same speed (6 km/h) was not significant with tibial nerve stimulation and only significant at P < 0.05 with CP nerve stimulation (0.30, 0.20). Also, the difference between standing (0.52) and slow walking (3 km/h; 0.41) with CP stimulation was not significant, but it was significant ( P < 0.01) with tibial nerve stimulation (0.68, 0.49). In conclusion, our findings indicate that spinal reciprocal inhibition decreases substantially with increasing speed and only changes to a lesser extent with task.

Spinal excitation and inhibition decrease as humans age

2004 ◽  
Vol 82 (4) ◽  
pp. 238-248 ◽  
Author(s):  
Aiko Kido ◽  
Naofumi Tanaka ◽  
Richard B Stein
Keyword(s):  
Human Subjects ◽  
Tibialis Anterior Muscle ◽  
Common Peroneal Nerve ◽  
Reciprocal Inhibition ◽  
H Reflex ◽  
Direct Stimulation ◽  
Voluntary Activity ◽  
Healthy Human ◽  
Wide Range ◽  
First Time

Although changes in the soleus H-reflex (an electrical analog of the tendon jerk) with age have been examined in a number of studies, some controversy remains. Also, the effect of age on inhibitory reflexes has received little attention. The purpose of this paper was to examine some excitatory and inhibitory reflexes systematically in healthy human subjects having a wide range of ages. We confirmed that both the maximum H-reflex (Hmax) and the maximum M-wave (Mmax) (from direct stimulation of motor axons) decrease gradually with age. The decrease in Hmax was larger so the Hmax/Mmax ratio decreased dramatically with age. Interestingly, the modulation of the H-reflex during walking was essentially the same at all ages, suggesting that the pathways that modulate the H-reflex amplitude during walking are relatively well preserved during the aging process. We showed for the first time that the short-latency, reciprocal inhibitory pathways from the common peroneal nerve to soleus muscle and from the tibial nerve to the tibialis anterior muscle also decreased with age, when measured as a depression of ongoing voluntary activity. These results suggest that there may be a general decrease in excitability of spinal pathways with age. Thus, the use of age-matched controls is particularly important in assessing abnormalities resulting from disorders that occur primarily in the elderly.Key words: H-reflex, reciprocal inhibition, age.

Minimizing Carry-Over Effects After Treatment Failure and Maximizing Therapeutic Outcome

2014 ◽  
Vol 222 (3) ◽  
pp. 171-178 ◽  
Author(s):  
Mareile Hofmann ◽  
Nathalie Wrobel ◽  
Simon Kessner ◽  
Ulrike Bingel
Keyword(s):  
Treatment Failure ◽  
Human Subjects ◽  
Subsequent Treatment ◽  
Clinical Samples ◽  
Administration Route ◽  
Healthy Human ◽  
Negative Experiences ◽  
Analgesic Treatment ◽  
Balanced Design ◽  
Carry Over

According to experimental and clinical evidence, the experiences of previous treatments are carried over to different therapeutic approaches and impair the outcome of subsequent treatments. In this behavioral pilot study we used a change in administration route to investigate whether the effect of prior treatment experience on a subsequent treatment depends on the similarity of both treatments. We experimentally induced positive or negative experiences with a topical analgesic treatment in two groups of healthy human subjects. Subsequently, we compared responses to a second, unrelated and systemic analgesic treatment between both the positive and negative group. We found that there was no difference in the analgesic response to the second treatment between the two groups. Our data indicate that a change in administration route might reduce the influence of treatment history and therefore be a way to reduce negative carry-over effects after treatment failure. Future studies will have to validate these findings in a fully balanced design including larger, clinical samples.

Detection of Soluble Fibrin Monomer Complexes in Blood by Means of Protamine Sulphate Test

1968 ◽  
Vol 20 (01/02) ◽  
pp. 044-049 ◽  
Author(s):  
B Lipiński ◽  
K Worowski
Keyword(s):  
Human Subjects ◽  
Coronary Thrombosis ◽  
Mean Value ◽  
Healthy Human ◽  
Protamine Sulphate ◽  
Soluble Fibrin ◽  
Fibrin Monomer ◽  
Dog Plasma ◽  
The Mean ◽  
Precipitable Protein

SummaryIn the present paper described is a simple test for detecting soluble fibrin monomer complexes (SFMC) in blood. The test consists in mixing 1% protamine sulphate with diluted oxalated plasma or serum and reading the optical density at 6190 Å. In experiments with dog plasma, enriched with soluble fibrin complexes, it was shown that OD read in PS test is proportional to the amount of fibrin recovered from the precipitate. It was found that SFMC level in plasma increases in rabbits infused intravenously with thrombin and decreases after injection of plasmin with streptokinase. In both cases PS precipitable protein in serum is elevated indicating enhanced fibrinolysis. In healthy human subjects the mean value of OD readings in plasma and sera were found to be 0.30 and 0.11, while in patients with coronary thrombosis they are 0.64 and 0.05 respectively. The origin of SFMC in circulation under physiological and pathological conditions is discussed.

Chronic stress decreases circulating endocannabinoid 2-arachidonoylglycerol in healthy human subjects

2015 ◽  
Author(s):  
Buqing Yi ◽  
Igor Nichiporuk ◽  
Matthias Feuerecker ◽  
Gustav Schelling ◽  
Alexander Chouker
Keyword(s):  
Chronic Stress ◽  
Human Subjects ◽  
Healthy Human ◽  
Healthy Human Subjects

scholarly journals Acacia Gum Is Well Tolerated While Increasing Satiety and Lowering Peak Blood Glucose Response in Healthy Human Subjects

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 618
Author(s):  
Riley Larson ◽  
Courtney Nelson ◽  
Renee Korczak ◽  
Holly Willis ◽  
Jennifer Erickson ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Human Subjects ◽  
Area Under The Curve ◽  
Soluble Fiber ◽  
Healthy Human ◽  
Glucose Response ◽  
Blood Glucose Response ◽  
Acacia Gum ◽  
Fiber Treatment ◽  
Healthy Human Subjects

Acacia gum (AG) is a non-viscous soluble fiber that is easily incorporated into beverages and foods. To determine its physiological effects in healthy human subjects, we fed 0, 20, and 40 g of acacia gum in orange juice along with a bagel and cream cheese after a 12 h fast and compared satiety, glycemic response, gastrointestinal tolerance, and food intake among treatments. Subjects (n = 48) reported less hunger and greater fullness at 15 min (p = 0.019 and 0.003, respectively) and 240 min (p = 0.036 and 0.05, respectively) after breakfast with the 40 g fiber treatment. They also reported being more satisfied at 15 min (p = 0.011) and less hungry with the 40 g fiber treatment at 30 min (p = 0.012). Subjects reported more bloating, flatulence, and GI rumbling on the 40 g fiber treatment compared to control, although values for GI tolerance were all low with AG treatment. No significant differences were found in area under the curve (AUC) or change from baseline for blood glucose response, although actual blood glucose with 20 g fiber at 30 min was significantly less than control. Individuals varied greatly in their postprandial glucose response to all treatments. AG improves satiety response and may lower peak glucose response at certain timepoints, and it is well tolerated in healthy human subjects. AG can be added to beverages and foods in doses that can help meet fiber recommendations.

Heart rate variability and baroreflex sensitivity are reduced in chronically undernourished, but otherwise healthy, human subjects

2003 ◽  
Vol 104 (3) ◽  
pp. 295-302 ◽  
Author(s):  
Mario VAZ ◽  
A.V. BHARATHI ◽  
S. SUCHARITA ◽  
D. NAZARETH
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Baroreflex Sensitivity ◽  
Human Subjects ◽  
Normal Weight ◽  
Autonomic Nerve ◽  
Total Power ◽  
Healthy Human ◽  
Frequency Power

Alterations in autonomic nerve activity in subjects in a chronically undernourished state have been proposed, but have been inadequately documented. The present study evaluated heart rate and systolic blood pressure variability in the frequency domain in two underweight groups, one of which was undernourished and recruited from the lower socio-economic strata [underweight, undernourished (UW/UN); n = 15], while the other was from a high class of socio-economic background [underweight, well nourished (UW/WN); n = 17], as well as in normal-weight controls [normal weight, well nourished (NW/WN); n = 27]. Baroreflex sensitivity, which is a determinant of heart rate variability, was also assessed. The data indicate that total power (0–0.4Hz), low-frequency power (0.04–0.15Hz) and high-frequency power (0.15–0.4Hz) of RR interval variability were significantly lower in the UW/UN subjects (P<0.05) than in the NW/WN controls when expressed in absolute units, but not when the low- and high-frequency components were normalized for total power. Baroreflex sensitivity was similarly lower in the UW/UN group (P<0.05). Heart rate variability parameters in the UW/WN group were generally between those of the UW/UN and NW/WN groups, but were not statistically different from either. The mechanisms that contribute to the observed differences between undernourished and normal-weight groups, and the implications of these differences, remain to be elucidated.

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