Comparisons of lumbar spine loads and kinematics in healthy and non-specific low back pain individuals during unstable lifting activities.

Evaluation of spinal loads in patients with low back pain (LBP) is essential to prevent further lumbar disorders. Many studies have investigated the relationship between lifting task variables and lumbar spine loads during manual lifting activities. The nature of the external load (stable versus unstable loads) is an important variable that has received less attention. Therefore, the present study aimed to measure trunk kinematics and estimate compressive-shear loads on the lumbar spine under lifting a 120 N stable load and 120 ± 13.63 N sensual unstable load in 16 healthy and 16 non-specific LBP individuals during lifting activities. The maximal lumbar loads were estimated using a quasi-static electromyography (EMG)-driven musculoskeletal model of the spine with 18 degrees of freedom (3 rotational degrees of freedom at 6 lumbar T12-S1 joints), seven rigid bodies (pelvis, thoracic, and five vertebrae), and 76 muscle fascicles. Moreover, the maximum velocity and acceleration of the thorax, lumbar, and pelvis, as well as their timing during the lifting activities were analyzed to investigate trunk kinematics. Results indicated that unstable, as compared to stable, lifting activities caused significantly larger peak L5-S1 (4677 N versus 4446 N, p = 0.021) and L4-L5 (4567 N versus 4366 N, p = 0.024) compressive loads in LBP individuals. Larger co-contraction of trunk muscles were found responsible for the larger compressive loads in LBP patients during unstable load lifting. The hand-load type (stable versus unstable) and group (LBP versus healthy) had no effects on kinematic variables and only the onset of peak kinematic parameters was significantly later in LBP patients. Slower movements with a change in movement strategy were observed in the LBP group. It was concluded that the nature of the external load adversely affected spinal loads in LBP patients thereby increasing the likelihood of further injury or pain.

Does endurance training affect IGF-1/IGFBP-3 and insulin sensitivity in patients with type 2 diabetes?

AIM: The aim of the present study was to determine whether six weeks of submaximal endurance training using a cycle ergometer would result in a modified serum insulin-like growth factor-1 (IGF-1), an insulin-like growth factor binding protein 3 (IGFBP-3), and insulin resistance in middle-aged men with type 2 diabetes (T2D). METHODS: Twenty male patients with T2D voluntarily participated in this study and were randomly divided into two groups: the training group (N.=10) and the control group (N.=10). The training protocol consisted of a 45-minutes cycling session/day, three days/week for six weeks with intensity 60-70% of the maximum heart rate. To examine the IGF-1 and the IGFBP-3, fasting blood glucose levels, and insulin resistance, blood sampling was performed before and immediately after the first and 18th sessions. The homeostatic model assessment (HOMA-IR) method was used to determine insulin resistance. RESULTS: Before the study began, no significant difference between the two groups was observed in the anthropometric and blood factors. After a session of aerobic exercise, IGF-1 and IGFBP-3 levels were significantly increased (153.79% and 64.3%, respectively), and fasting glucose and insulin resistance levels were significantly decreased (15.82% and 27.82%, respectively); however, the changes resulting from a six-week training period were not significant. CONCLUSION: According to the present study, one session of aerobic exercise for middle-aged men with T2D leads to increased IGF-1 and IGFBP-3, and to decreased fasting glucose and insulin resistance. Considering the lack of changes after a six-week training, it seems that the amount of change depends on subjects' fitness level and exercise parameters. From a clinical point of view, the beneficial effects of acute exercise inT2D subjects show that such exercises should be part of the daily program for them.

Hormonal responses of combining endurance-resistance exercise in healthy young men.

AIM: This study investigated the influence of resistance (R) following endurance (E) exercise or ER on acute hormonal responses, such as growth hormone (GH), total testosterone (TT), free testosterone (FT), IGF-1, and cortisol. METHODS: Ten healthy young men with an average age of 23.9 years (±0.7 y), a height of 175 cm (±3.3 cm), a weight of 74.4 kg (±4.3 kg), and a body mass index of 25.5 kg/m2 (±0.65 kg/m2) participated in this study. All of the participants took part in four protocols (R, E, ER, and control) in separate sessions with at least 1-week intervals. Blood samples were collected before, immediately after exercise, and 15 minutes after exercise in the R, E, ER, and control group protocols. RESULTS: GH, lactate, TT, and FT increased in the R protocol, and GH, lactate, FT, and IGF-1 increased significantly in the E and ER protocols (P<0.05). FFA increased only after the E protocol (P<0.05). Cortisol significantly decreased in the ER, E, and control group protocols (P<0.05). CONCLUSION: In conclusion GH, TT and cortisol responses to R following E exercise were reduced. This effect might be due to increase in FFA. However It seems that IGF-1 has not inhibited by FFA.