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Reactive Strength Index: A Poor Indicator of Reactive Strength?

Robin Healy, Ian C. Kenny, and Andrew J. Harrison

accomplish this, the concept of reactive strength was developed. 6 Reactive strength has been described in numerous ways throughout the literature. The most commonly used definition is the capacity of an athlete to bear a stretch load and subsequently switch rapidly from an eccentric to concentric muscle

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Modulation of Anticipatory Postural Adjustments in a Complex Task under Different Temporal Constraints

Nabil Ilmane and Jacques LaRue

The aim of this experiment was to explore the behavioral effects of various temporal pressures on the anticipatory postural adjustments (APAs) in a complex task. Eighteen handball players performed a handball direct throw in three conditions of temporal pressure: (1) a reactive condition (RC), the throw was initiated as quickly as possible following a visual stimulus; (2) an anticipation-coincidence condition (AC), by synchronizing the impact of the ball with the passage of a visual mobile on a target; and (3) a self-initiated (SI) throw. The whole-body postural oscillation and the acceleration of the wrist were measured before and during the throwing action. Results showed that the delays between the onsets of the postural and focal activities were significantly different between RC and both the SI and the AC conditions. Movement time, time to peaks (negative and positive), are shorter in the RC, intermediate in the AC, and longer in the SI condition. Variability was significantly larger in AC in comparison with RC and SI. These results support the existence of different control modes triggered by the temporal pressure; they demonstrate that these control modes can be generalized to complex intentional movements such as the throwing skill and to an anticipation-coincidence situation.

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Lifetime Stressor Exposure and Psychophysiological Reactivity and Habituation to Repeated Acute Social Stressors

Ella McLoughlin, Rachel Arnold, Paul Freeman, James E. Turner, Gareth A. Roberts, David Fletcher, George M. Slavich, and Lee J. Moore

(e.g., genetics), cumulative lifetime stressor exposure (e.g., past and current stressors), and protective factors (e.g., social, psychological, and behavioral processes); (b) psychophysiological stress responses (e.g., cognitive appraisals and cardiovascular reactivity); and (c) biological aging and

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Biomechanical Determinants of the Reactive Strength Index During Drop Jumps

Kristof Kipp, Michael T. Kiely, Matthew D. Giordanelli, Philip J. Malloy, and Christopher F. Geiser

The Reactive Strength Index (RSI) is a measure often used to quantify dynamic lower-extremity performance during a drop jump (DJ). 1 – 3 The RSI represents a highly reliable (ie, intraclass correlation coefficient > .90) and simple index of performance that is also easy to measure and interpret. 4

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Reactivity to Accelerometer Measurement of Children With Visual Impairments and Their Family Members

Xihe Zhu and Justin A. Haegele

Wearable devices such as accelerometers and pedometers are commonly used in research to measure physical activity ( Cain, Sallis, Conway, Van Dyck, & Calhoon, 2013 ). One concern with using wearable devices is reactivity, which refers to the phenomenon in which research participants alter their

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Measurement Reactivity in Ecological Momentary Assessment Studies of Movement-Related Behaviors

Jaclyn P. Maher, Danielle Arigo, Kiri Baga, Gabrielle M. Salvatore, Kristen Pasko, Brynn L. Hudgins, and Laura M. König

may introduce changes in one’s behavior, cognitions, or beliefs as a result of its measurement—a phenomenon known as measurement reactivity ( French & Sutton, 2010 ). Measurement reactivity has implications for behavioral science, as it is crucial to determine whether changes in constructs of interest

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Standing Versus Stepping—Exploring the Relationships Between Postural Steadiness and Dynamic Reactive Balance Control

Michelle R. Tanel, Tyler B. Weaver, and Andrew C. Laing

control), the size of the base of support must be increased. Following external postural perturbations (eg, a simulated trip), older adults commonly respond with 1 or more reactive steps. 12 , 13 Increased step length has been demonstrated to enhance balance control abilities 14 ; however, older adults

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The Effect of Active Physical Training Interventions on Reactive Postural Responses in Older Adults: A Systematic Review

Brian M. Moore, Joseph T. Adams, Sallie Willcox, and Joseph Nicholson

to rapidly and appropriately generate corrective muscle forces to recover from imbalance ( Jacobs & Horak, 2007 ; Shumway-Cook & Woollacott, 2017 ). Such reactions are referred to as compensatory or reactive postural responses, defined as the ability to recover from instability through a rapid

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A 5-Week Guided Active Play Program Modulates Skin Microvascular Reactivity in Healthy Children

Asal Moghaddaszadeh, Emilie Roudier, Heather Edgell, Agnes Vinet, and Angelo N. Belcastro

participation in GAP lowers children’s systolic and diastolic blood pressure, the impact on microvascular function is unknown. Hence, we proposed to assess whether GAP can induce changes in the cutaneous microvascular reactivity in normal weight children when engaged in a 5-week community-based summer day camp

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Reactive Strength as a Metric for Informing Return-to-Sport Decisions: A Case-Control Study

Jorg Teichmann, Kim Hébert-Losier, Rachel Tan, Han Wei Lem, Shabana Khanum, Ananthi Subramaniam, Wee-Kian Yeo, Dietmar Schmidtbleicher, and Christopher M. Beaven

identified as being associated with knee valgus angles during cutting movements 19 and performance indicators in contact sport 20 in high-level athletes. Thus, we hypothesized that a reactive strength metric obtained from a unilateral DJ may provide a more relevant and informative metric to assess