Study on Electromyographic Characteristics of Neck Muscles in College Students with Chronic Neck Pain

Objective:To provide new insights for the evaluation and diagnosis of chronic neck pain(CNP).Methods:22 patients with CNP and 22 healthy individuals were recruited from South China Normal University,who were all college students.The subjects'neck extensor muscle strength in the head neutral position,the natural anteversion position,and the maximum forward flexion position were measured by an isometric muscle strength tester respectively.The neck extensor strength of CNP patients and healthy subjects were compared.Results:In the neutral position,the maximum isometric muscle strength of neck extensor muscles was 12.31 kg for CNP patients and 15.16 kg for healthy individuals,resulting in a ratio of 81%strength in patients compared to healthy subjects.This difference was highly significant(P<0.000).In the natural anteversion position,the respective values were 12.6 kg for CNP patients and 15.05 kg for healthy individuals,with a ratio of 83%,and a significant difference between groups(P<0.001).In the maximum forward flexion position of the head,the values were 13.36 kg for CNP patients and 16.15 kg for healthy individuals,with a ratio of 82%,and a highly significant difference(P<0.000).Conclusion:The neck extensor muscle strength levels in college students with CNP were significantly lower compared to healthy college students across all measured positions.

Sensory quality of meat from eight different types of cattle in relation with their biochemical characteristics

The present study compared eight breeds of cattle differing in gender （heifers, buls and steers） to determine associations between muscle characteristics and meat sensory qualities of theLongissimus thoracis muscle. Animal types differed in al the muscle characteristics and sensory qualities. Many correlations among muscle characteristics and among sensory qualities were consistent for most animal types. Isocitrate dehydrogenase （ICDH） activities alowed discrimination of muscles with respect to myosin heavy chain （MyHC）-I proportions for al animal types. Lactate dehydrogenase （LDH） and phos-phofructokinase （PFK） activities were positively correlated for most animal types. Overal liking was correlated with beef lfavour and abnormal lfavour in al animal types and with global tenderness for al animal types except for Charolais cross breed steers. For al animal types except for Angus×Friesian heifers, beef lfavour and abnormal lfavour were negatively correlated. Overal liking was not correlated with juiciness. PFK, ICDH and citrate synthase （CS） activities were strongly associated with tenderness, beef lfavour and overal liking when average values for al animal types were used. However, associations between muscle characteristics and sensory qualities within animal types were weak and inconsistent.

Dietary L-arginine supplementation influences the muscle fiber characteristics and meat quality of Mongolian sheep through the NO/AMPK/PGC-1α pathway

L-arginine serves as a substrate for the production of nitric oxide(NO)in animals,and it can also impact muscle fiber characteristics and meat quality in these animals.The present study was designed to explore the effects of adding 1%L-arginine to a basal diet regimen on the muscle fiber characteristics and meat quality of Mongolian sheep.Dietary L-arginine supplementation reduced shear force in the longissimus thoracis(LT)and increased a*in biceps femoris(BF)muscles(p<0.05).L-arginine supplementation also increased the proportion of type IIA muscle fiber in the LT(p<0.05)and type I muscle fiber in the BF(p<0.05)while reducing both the diameter and CSA of type IIB muscle fiber in both the LT and BF(CSA in LT,p<0.01;all others,p<0.05).L-arginine treatment was also associated with the upregulation of MyHC IIa(LT),MyHC I(BF),nNOS(LT&BF),AMPKα1(BF),PGC-1α(LT&BF)(PGC-1αin BF,p<0.01;all others,p<0.05),together with an increase in nNOS content(LT,p<0.01;BF,p<0.05).Dietary L-arginine supplementation was associated with a significant increase in the post-slaughter tenderness of lamb meat,which is related to transitions in muscle fiber types.The gene expression and nNOS analysis results generated herein further indicate that this effect is mediated by the NO/AMPK/PGC-1αpathway.Further studies are thus warranted to provide further insight into the role that NO signaling plays in controlling the associations between L-arginine,muscle fiber characteristics,and meat quality.

Standardized ileal digestible lysine requirements based on growth performance and histochemical characteristics of male broilers from 10 to 21 d of age

The growth performance and histochemical characteristics of breast muscle fibers were used to estimate the standardized ileal digestible(SID)Lys requirements for 10-to 21-d-old male broilers.Three hundred and sixty 10-d-old Ross 308 broilers(290±16.6 g)were allocated to 6 diets in a randomized complete block design with 6 replicate cages per treatment and 10 birds per cage.The 6 experimental diets were formulated to contain equally spaced increasing levels of SID Lys from 0.86%to 1.36%.The data were analyzed using the MIXED procedure of SAS.The Lys requirements were estimated by the NLIN procedure of SAS.An increase in dietary SID Lys from 0.86%to 1.36%resulted in a quadratic increase(P<0.05)in body weight gain(BWG),gain to feed ratio(G:F),breast weight,muscle cross-sectional area(MCSA),and fiber area.The SID Lys requirements based on the one-slope broken-line,quadratic line,the first intercept between the plateau of the one-slope broken-line and quadratic-line models and 95%of the upper asymptote of the quadratic-line model were estimated to be 1.01%,1.19%,1.08%,and 1.13%for BWG,1.06%,1.22%,1.11%,and 1.16%for G:F,1.10%,1.29%,1.19%,and 1.22%for breast weight,1.06%,1.22%,1.12%,and 1.16%for MCSA,and 1.14%,1.22%,1.16%,and 1.16%for breast muscle fiber area,respectively.It was concluded that the SID Lys requirements for broilers at the age of 10 to 21 d depended on the response variables used for estimation,and that histochemical characteristics of breast muscle fibers could be good indicators for estimating SID Lys requirements.