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American Journal of Sports Science and Medicine
Number of Followers: 39

This is an Open Access Journal

Open Access journal
ISSN (Print) 2333-4592 - ISSN (Online) 2333-4606
Published by Science and Education Publishing

[75 journals]

Effect of One-side-shoulder Bag Holding with Different Weights on Center
of Gravity Shaking during a Standing Posture in Young Women
- Authors: Yoshinori Nagasawa; Shin-ichi Demura, Hiroshi Hirai
  Pages: 1 - 5
  Abstract: Center of gravity shaking (CGS) changes constantly during a standing posture and its variation increases depending on the disturbance stimulus. One-side-shoulder bag (OSB) holding with a heavy weight makes the standing posture unstable because it imposes burden on one side of the shoulder and/or lower back. It is assumed that the effect of OSB on CGS differs by bag weight and the habitual and non-habitual use of one shoulder. This study aimed to examine the effect of different weights and holding shoulders on CGS during OSB in a standing posture in 30 healthy young women aged 21-24 years. The experimental conditions were relative weight loads (0% [non-bag holding], 5%, 10%, and 15% of body mass [BM]) and bag holding shoulder (habitual and non-habitual). The participants maintained a Romberg posture (standing posture with feet closed) with eyes open for 1 minute on the measurement equipment in the above-mentioned eight conditions. The x-axis, y-axis, and total trajectory lengths and outer peripheral area were transmitted to a computer at a sampling rate of 20 Hz. The measurement order was randomized for the different weight loads and holding shoulders. Two measurements were obtained for each condition with a 1-min rest between measurements. The two measurements were then averaged. A two-way analysis of variance (ANOVA) showed that the x-axis, y-axis, and total trajectory lengths were significantly higher for weight loads of 10% BM and above. The outer peripheral area value was significantly lower for the habitual holding shoulder. The 10% and 15% BM weights had significantly higher outer peripheral area values compared with the 0% BM weight, and the 15% BM weight had significantly higher outer peripheral area values compared with the 5% and 10% BM weights. The x-axis, y-axis, and total trajectory lengths and outer peripheral area become greater as bag weight increases over 10% BM. OSB holding leads to a larger outer peripheral area in the non-habitual holding shoulder compared with the habitual holding shoulder in young women.
  PubDate: 2022-05-17
  DOI: 10.12691/ajssm-10-1-1
  Issue No: Vol. 10, No. 1 (2022)
Acute Hormonal Responses to Free Weight and Machine Resistance Exercise
- Authors: Andrew C. Fry; Justin X. Nicoll, Dimitrije Cabarkapa, Paige N. Stephens
  Pages: 6 - 11
  Abstract: This study examined acute hormonal responses to multi-joint free weight exercise and single joint machine exercise. Six weight-trained males performed 3 sets of 10 repetitions at 70% of 1RM with one minute rest between each set on either the barbell squat (FW) or three single joint machine weight exercises (MW; i.e., leg curl, leg extension, back extension) using similar primary movers in a randomly-ordered crossover design. Testosterone (T), cortisol (C), growth hormone (GH), and lactate (HLa) were determined from blood samples 15 minutes before (PRE) and 5 minutes after (POST) each exercise session performed at the same time of day. The MW group completed significantly more estimated external work than the FW group (J; MW = 30776±2152, FW = 19728±2399), but the FW protocol resulted in a greater HLa response (mmol.L-1; MW, PRE = 1.2±0.1, POST = 6.7±0.7; FW, PRE = 1.5±0.1, POST = 10.5±1.6). Both exercise modalities exhibited similar increases in T (nmol.L-1; MW, PRE = 13.4±2.7, POST = 17.6±2.9; FW, PRE = 15.5±2.8, POST = 17.6±3.5) and GH (g.L-1; MW, PRE = 1.4±0.3, POST = 6.8±3.3; FW, PRE = 1.1±0.1, POST = 4.3±2.0), despite the lower work performed by the FW protocol. Although C increased for both protocols, the FW session induced a greater C response (nmol.L-1; MW, PRE = 463.2±147.8, POST = 448.1±144.1; FW, PRE = 444.4±174.0, POST = 696.9±220.4). While using similar muscle mass, these results suggest that the acute hormonal response is partially dependent on exercise modality. Despite completing less estimated external work, FW exercise protocol yielded similar or greater endocrine responses when compared to MW resistance training modality.
  PubDate: 2022-06-01
  DOI: 10.12691/ajssm-10-1-2
  Issue No: Vol. 10, No. 1 (2022)
Estimating Athletes’ Centre of Mass as Presented on Ancient Greek
Pottery Depictions
- Authors: Andreas G. Bourantanis; Nikitas N. Nomikos, Constantinos C. Trompoukis, Weijie W. Wang
  Pages: 12 - 16
  Abstract: Combat sports pose a discrete thesis in terms of biomechanics among the majority of the sport activities. This research aims to identify and study the position of Centre of Mass (CoM) in ancient Greek Athletes who participated in combat sports, especially in Pankration. This project was carried out by analyzing figures drawn on ancient pottery. The study calculated the CoM using innovative software and programming: OpenPose, Sublime text, Python programming language, and Matplotlib library. According to the results, the study succeeded (for the first time globally) in calculating the CoM of ancient Pankratiasts during the contests.
  PubDate: 2022-07-13
  DOI: 10.12691/ajssm-10-1-3
  Issue No: Vol. 10, No. 1 (2022)

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