Author Identifier

Brusco CM

https://orcid.org/0000-0002-2013-1652

Date of Award

2022

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy (Joint-ECU host)

School

School of Medical and Health Sciences

First Supervisor

Anthony John Blazevich

Second Supervisor

Ronei Silveira Pinto

Abstract

Biceps femoris long head (BFlh) fascicle length (Lf), fascicle angle (FA), and muscle thickness (MT) were assessed at rest and during dynamic contractions using B-mode ultrasound imaging. The assessments were performed in men and women with no previous hamstring strain injury. Volunteers visited the laboratory for two separate data collection sessions (Day 1 and Day 2) relating to two independent projects, seven days apart at the same time of day for test-retest measurements of the static assessments. For the dynamic assessments, familiarization with the isokinetic concentric and eccentric knee flexion exercises were performed on Day 1. On Day 2, BFlh Lf, FA and MT were assessed in real time using two serially aligned ultrasound devices whilst performing consecutive concentric and eccentric knee flexions at 30°/s and 180°/s.

To acquire images at rest, ultrasound imaging was performed using extended field-of-view (EFOV) and static image acquisition sequences of four single images acquired in-series along the muscle. From these images, Lf was assessed using seven methods: EFOV, Collage, manual linear extrapolation, and using four different trigonometric equations, and then FA and MT were measured in EFOV, Collage, and Single images. Lf, FA and MT measured on Days 1 and 2 were not different (p > 0.05) for any method, reliabilities were very high (ICC: 0.91-0.98), and correlations were strong ( ≥ 0.84). Significant correlations (p < 0.05; r=0.67-0.98) were found between EFOV and the other measurement techniques for Lf, FA and MT. The Collage method had the highest reliability for Lf, and highest rank order and correlation with EFOV. The Collage method can therefore be recommended for use if the methodology presented herein is followed.

For assessments during dynamic contractions, participants performed consecutive concentric and eccentric contractions at 30°/s and 180°/s whilst in vivo muscle function was recorded using two in-series transducers. At 30°/s both submaximal (55% maximum) and maximal contractions were performed whilst at 180°/s only maximal contractions were performed both before and after fatiguing exercise. Ultrasound videos were exported and edited to create a single, synchronized video and three fascicles were analyzed through the range of motion. Changes during concentric and eccentric contractions (Δ) in Lf, FA and MT at short (60-90° knee angle; 0° full knee extension) and long (0-30°) muscle lengths and across the full knee flexion range were measured and compared. Comparisons were made within exercises performed with the same contraction velocity. When fascicle behaviors were compared during submaximal and maximal concentric and eccentric contractions at 30°/s, greater ΔLf was observed at longer muscle length during both eccentric and concentric contractions (p=0.01), and this alteration was greater during eccentric contractions (p=0.02) at longer muscle lengths (p < 0.001). Greater ΔFA was observed at long length during eccentric contractions (p=0.02). When whole range of motion was analyzed, greater ΔMT was observed (p=0.03) in concentric contractions. When fascicle behavior was compared in the maximal contractions at 180°/s before and after fatiguing exercise, greater ΔLf was observed in the eccentric contraction at the long muscle length (p = 0.01), ΔFA was greater at short muscle lengths in the concentric contractions (p=0.02) and at long muscle lengths (p=0.006) and at full range of motion (p=0.006) during eccentric contractions. Less ΔFA was detected across all contractions (p < 0.05) after the fatiguing exercise when measured through the full range of motion. Greater dynamic torque was observed at long muscle lengths, during eccentric contraction, and before the fatiguing exercise (p < 0.05).

Although the six different techniques used to estimate Lf during rest provided values similar to EFOV, the Collage sonographic method provided the most accurate and reliable results and is therefore recommended for BFlh architectural analysis when EFOV is not available. Greater ΔLf and ΔFA were observed for a given joint rotation increment during submaximal and maximal eccentric contractions at long muscle lengths. The increased fascicle strain at long muscle length might contribute to both increased metabolic stress, and therefore longer-term muscle hypertrophy, and to muscle strain injuries.

Comments

Author also known as Clarissa Müller Brusco

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