Concept: Relative Strength Index
This review discusses previous literature that has examined the influence of muscular strength on various factors associated with athletic performance and the benefits of achieving greater muscular strength. Greater muscular strength is strongly associated with improved force-time characteristics that contribute to an athlete’s overall performance. Much research supports the notion that greater muscular strength can enhance the ability to perform general sport skills such as jumping, sprinting, and change of direction tasks. Further research indicates that stronger athletes produce superior performances during sport specific tasks. Greater muscular strength allows an individual to potentiate earlier and to a greater extent, but also decreases the risk of injury. Sport scientists and practitioners may monitor an individual’s strength characteristics using isometric, dynamic, and reactive strength tests and variables. Relative strength may be classified into strength deficit, strength association, or strength reserve phases. The phase an individual falls into may directly affect their level of performance or training emphasis. Based on the extant literature, it appears that there may be no substitute for greater muscular strength when it comes to improving an individual’s performance across a wide range of both general and sport specific skills while simultaneously reducing their risk of injury when performing these skills. Therefore, sport scientists and practitioners should implement long-term training strategies that promote the greatest muscular strength within the required context of each sport/event. Future research should examine how force-time characteristics, general and specific sport skills, potentiation ability, and injury rates change as individuals transition from certain standards or the suggested phases of strength to another.
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- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published over 4 years ago
Researchers have demonstrated that increases in strength result in increases in athletic performance, although the development of strength is still neglected in some sports. Our aim was to determine whether a simple in-season strength training program would result in increases in maximal squat strength and short sprint performance, in professional soccer players. Professional soccer players (n=17, age = 18.3 ± 1.2 years, height = 1.79 ± 0.06 m, body mass (BM) = 75.5 ± 6.1 kg) completed one repetition maximum (1RM) back squat and sprint tests (5-, 10-, 20 m) before and after a six-week (2 x week) in-season strength training (85-90% 1RM) intervention. Strength training resulted in significant improvements in absolute and relative strength (pre: 125.4 ± 13.8 kg, post 149.3 ± 16.2 kg, p < 0.001, Cohen's d = 0.62; 1RM/BM pre: 1.66 ± 0.24 kg.kg-1, post 1.96 ± 0.29 kg.kg-1, p < 0.001, Cohen's d = 0.45; respectively). Similarly, there were small yet significant improvements in sprint performance over 5 m (pre 1.11 ± 0.04 s, post 1.05 ± 0.05 s, p < 0.001, Cohen's d = 0.55) 10 m (pre 1.83 ± 0.05 s, post 1.78 ± 0.05 s, p < 0.001, Cohen's d = 0.45) and 20 m (pre 3.09 ± 0.07 s, post 3.05 ± 0.05 s, p < 0.001, Cohen's d = 0.31). Changes in maximal squat strength appear to be reflected in improvements in short sprint performance highlighting the importance of developing maximal strength to improve short sprint performance. Moreover this demonstrates that these improvements can be achieved during the competitive season in professional soccer players.
We examined population-based surveillance data from the Tennessee Emerging Infections Program to determine whether neighborhood socioeconomic status was associated with influenza hospitalization rates. Hospitalization data collected during October 2007-April 2014 were geocoded (N = 1,743) and linked to neighborhood socioeconomic data. We calculated age-standardized annual incidence rates, relative index of inequality, and concentration curves for socioeconomic variables. Influenza hospitalizations increased with increased percentages of persons who lived in poverty, had female-headed households, lived in crowded households, and lived in population-dense areas. Influenza hospitalizations decreased with increased percentages of persons who were college educated, were employed, and had health insurance. Higher incidence of influenza hospitalization was also associated with lower neighborhood socioeconomic status when data were stratified by race.
This study determines the major difference between rumors and non-rumors and explores rumor classification performance levels over varying time windows-from the first three days to nearly two months. A comprehensive set of user, structural, linguistic, and temporal features was examined and their relative strength was compared from near-complete date of Twitter. Our contribution is at providing deep insight into the cumulative spreading patterns of rumors over time as well as at tracking the precise changes in predictive powers across rumor features. Statistical analysis finds that structural and temporal features distinguish rumors from non-rumors over a long-term window, yet they are not available during the initial propagation phase. In contrast, user and linguistic features are readily available and act as a good indicator during the initial propagation phase. Based on these findings, we suggest a new rumor classification algorithm that achieves competitive accuracy over both short and long time windows. These findings provide new insights for explaining rumor mechanism theories and for identifying features of early rumor detection.
- International journal of sports physiology and performance
- Published almost 4 years ago
Maximum- and reactive-strength qualities both have important roles in athletic movements and sporting performance. Very little research has investigated the relationship between maximum-strength and reactive-strength. The aim of this study was to investigate the relationship between maximum-strength (isometric mid-thigh pull peak force; IMTP PF) and reactive-strength (drop-jump reactive-strength index; DJ-RSI) variables at 0.3 m, 0.4 m, 0.5 m and 0.6 m box heights. A secondary aim investigated the between- and within-group differences in reactive-strength characteristics between relatively ‘strong’ and ‘weak’ athletes. Forty-five collegiate athletes across various sports were recruited to participate in the study (age: 23.7 ± 4.0 years; mass: 87.5 ± 16.1 kg; height: 1.80 ± 0.08 m). Pearson’s correlation results showed that there was a moderate association (r = 0.302 - 0.431) between maximum-strength variables (absolute, relative & allometric scaled PF) and RSI at 0.3, 0.4, 0.5 and 0.6 m (p ≤ 0.05). In addition, two-tailed independent samples t tests showed that relatively stronger athletes (n = 11; 49.59 ± 2.57 N·kg-1) had significantly larger RSI than weaker athletes (n = 11; 33.06 ± 2.76 N·kg-1) at 0.4 m (Cohen’s d = 1.02), 0.5 m (d = 1.21) and 0.6 m (d = 1.39) (p ≤ 0.05). Weaker athletes also demonstrated significant decrements in RSI as eccentric stretch loads increased from 0.3 to 0.6 m box heights, whereas strong athletes were able to maintain their reactive-strength ability. This research highlights that in specific sporting scenarios, where there are high eccentric stretch-loads and fast stretch-shortening cycle (SSC) demands, an athlete’s reactive-strength ability may be dictated by their relative maximal-strength, specifically their eccentric strength.
An Investigation into the Relationship between Maximum Isometric Strength and Vertical Jump Performance
- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published over 5 years ago
Research has demonstrated a clear relationship between dynamic strength and vertical jump performance; however, the relationship of isometric strength and vertical jump performance has been studied less extensively. The aim of this study was to determine the relationship between isometric strength and performance during the squat jump (SJ) and countermovement jump (CMJ). Twenty-two male collegiate athletes (mean ± SD; age = 21.3 ± 2.9 years; height = 175.63 ± 8.23 cm; body mass = 78.06 ± 10.77 kg) performed isometric mid-thigh pulls (IMTP) to assess isometric peak force (IPF), maximum rate of force development (mRFD) and impulse (I100, I200, and I300). Force time data, collected during the vertical jumps, was used to calculate peak velocity (PV), peak force (PF), peak power (PP), and jump height. Absolute IMTP measures of IMP showed the strongest correlations with VJ PF(r = 0.43 - 0.64, p ≤ 0.05), and VJ PP (r = 0.38 - 0.60, p ≤ 0.05). No statistical difference was observed in CMJ height (0.33 ± 0.05 m vs. 0.36 ± 0.05 m; p = 0.19; ES = -0.29) and SJ height performance (0.29 ± 0.06 m vs. 0.33 ± 0.05 m vs.; p = 0.14; ES = -0.34) when comparing stronger to weaker athletes. The results of this study illustrate that absolute IPF and IMP are related to VJ PF and PP, but not VJ height. As stronger athletes did not jump higher than weaker athletes, dynamic strength tests may be more practical methods of assessing the relationships between relative strength levels and dynamic performance in collegiate athletes.
Self-Certified Sickness Absence among Young Municipal Employees-Changes from 2002 to 2016 and Occupational Class Differences
- International journal of environmental research and public health
- Published almost 3 years ago
We examined changes in self-certified, one-to-three day sickness absence (SA) among young employees from 2002 to 2016 and the magnitude of occupational class differences during that period. All 18-34-year-old employees of the City of Helsinki, Finland were included (2002-2016, n = ~11,725 per year). Employer’s personnel and SA registers were used. Occupational class was categorized to four groups. Changes in self-certified SA from 2002 to 2016 were analyzed with Joinpoint regression and the magnitudes of occupational class differences were estimated with the relative index of inequality (RII). Most of the trends first increased and turned to decrease in 2007/2010. Managers and professionals had the least amount of SA, but steadily increasing trends were observed among men. Self-certified SA followed only partially the typical socioeconomic gradient, as routine non-manuals had the highest levels of SA. The magnitude of occupational class differences in self-certified SA was stable during the study period only among women. Self-certified SA and occupational class differences have increased in recent years among men in the lower occupational classes. Socioeconomic differences exist in self-certified SA among young employees, but gradient is only partial. Overall, high amounts of self-certified SA especially in the lower occupational classes require further studies and preventive measures.
- Academic emergency medicine : official journal of the Society for Academic Emergency Medicine
- Published almost 3 years ago
Emergency department (ED) acuity is the general level of patient illness, urgency for clinical intervention, and intensity of resource use in an ED environment. The relative strength of commonly used measures of ED acuity is not well understood.
The processing mechanism of verbs-actions and nouns-objects is a central topic of language research, with robust evidence for behavioral dissociation. The neural basis for these two major word and/or conceptual classes, however, remains controversial. Two experiments were conducted to study this question from the network perspective. Experiment 1 found that nodes of the same class, obtained through task-evoked brain imaging meta-analyses, were more strongly connected with each other than nodes of different classes during resting-state, forming segregated network modules. Experiment 2 examined the behavioral relevance of these intrinsic networks using data from 88 brain-damaged patients, finding that across patients the relative strength of functional connectivity of the two networks significantly correlated with the noun-object vs. verb-action relative behavioral performances. In summary, we found that verbs-actions and nouns-objects are supported by separable intrinsic functional networks and that the integrity of such networks accounts for the relative noun-object- and verb-action-selective deficits.