Comparison of linea alba length and core-muscles engagement during core and lower back orientated exercises.

BACKGROUND: A comparison of Linea Alba (LA) length and engagement of the Transverse Abdominis (TrA), External Oblique (EO) and Internal Oblique (IO) between core-orientated and lower back orientated exercises (e.g. glute bridge and hip extension) is lacking. Therefore, the aim of this study was to compare the length of the LA and the engagement of TrA, EO and IO when performing the prone plank, bird dog, dead bug, lateral plank, glute bridge and hip extension. METHODS: Thirteen apparently healthy participants volunteered to this study. Ultrasound scanning of the anterior and antero-lateral abdominal walls at baseline and whilst performing prone plank, bird dog, dead bug, lateral plank, glute bridge and hip extension exercises was performed. LA length and thickness of the TrA, EO and IO were measured from ultrasound images. RESULTS: LA length (p = 0.77) and TrA thickness (p = 0.23) were not different between exercises. EO thickness was larger for the lateral plank compared to the bird dog (p = 0.01, d = 1.73), glute bridge (p < 0.01, d = 2.64), and hip extension (p < 0.01, d = 1.89). The dead bug was also larger in comparison to the glute bridge (p < 0.01, d = 2.05) and to the hip extension (p = 0.01, d = 1.45). For the IO thickness, the lateral plank was larger than the bird dog (p = 0.03, d = 1.21) and the dead bug (p = 0.04, d = 1.12). CONCLUSION: No difference was observed between exercises for the length of the LA or for the thickness of the TrA, which suggests that this muscle is similarly engaged in the assessed exercises, leading to a consistent stretch for the LA.

Effects of exercise mode in knee cartilage thickness.

BACKGROUND: It is unclear how cycling and running would differ in terms of changes in cartilage thickness. Also, given squats are a popular type of exercise used to strengthen lower limbs, it is critical to assess if loads used during resisted training could lead to changes in cartilage cushioning properties. Therefore, the purpose of this study was to compare the effects of exercise mode in knee cartilage thickness. METHODS: This study utilized a randomized cross-over design with repeated measures. All sessions were completed between 48hrs and seven days, at the same time of the day. Fourteen (seven males and seven females) apparently healthy participants without musculoskeletal or neurological diseases volunteered for the study. Participants were assessed after squats and functional exercises (n = 18 knees) or after running and cycling (n = 10 knees). All ultrasound images were collected at participants' arrival in the laboratory (Baseline), after warm-up (Pre-exercise), after the completion of each exercise protocol (Post-exercise), and at five (5-min) and 10 minutes (10-min) after exercise. RESULTS: Cartilage thickness did not change after squats performed with 60% of 1-RM or after a set of three functional exercises (i.e. sit-to-stand, lunges, and step-ups; p = 0.68). However, longer duration exercises (i.e. cycling and running) led to increases in cartilage thickness after 5-min from the completion of the exercise (p = 0.02). CONCLUSION: Knee cartilage may have capacity to sustain short-term cyclical loads applied during exercise (i.e. squats and functional exercises) but not to moderate duration exercises (i.e. cycling and running).