Effect of suspension systems on the physiological and psychological responses to sub-maximal biking on simulated smooth and bumpy tracks

The aim of this study was to compare the physiological and psychological responses of cyclists riding on a hard tail bicycle and on a full suspension bicycle. Twenty males participated in two series of tests. A test rig held the front axle of the bicycle steady while the rear wheel rotated against a heavy roller with bumps (or no bumps) on its surface. In the first series of tests, eight participants (age 19 – 27 years, body mass 65 – 82 kg) were tested on both the full suspension and hard tail bicycles with and without bumps fitted to the roller. The second series of test repeated the bump tests with a further six participants (age 22 – 31 years, body mass 74 – 94 kg) and also involved an investigation of familiarization effects with the final six participants (age 21 – 30 years, body mass 64 – 80 kg). Heart rate, oxygen consumption (VO<sub>2</sub>), rating of perceived exertion (RPE) and comfort were recorded during 10 min sub-maximal tests. Combined data for the bumps tests show that the full suspension bicycle was significantly different (P < 0.001) from the hard tail bicycle on all four measures. Oxygen consumption, heart rate and RPE were lower on average by 8.7 (s = 3.6) ml · kg<sup>-1</sup> · min<sup>-1</sup>, 32.1 (s = 12.1) beats · min<sup>-1</sup> and 2.6 (s = 2.0) units, respectively. Comfort scores were higher (better) on average by 1.9 (s = 0.8) units. For the no bumps tests, the only statistically significant difference (P = 0.008) was in VO<sub>2</sub>, which was lower for the hard tail bicycle by 2.2 (s = 1.7) ml · kg-1 · min<sup>-1</sup>. The results indicate that the full suspension bicycle provides a physiological and psychological advantage over the hard tail bicycle during simulated sub-maximal exercise on bumps

Mountain bicycle rear suspension dynamics and their effect on cyclists

The research documented in this report was conducted to understand better the anomaly between the predicted benefits of rear suspension systems for mountain bicycles and the preferred choice of rigid framed mountain bicycles by professional cyclists in the Union Cycliste Internationale (U.C.I.) world cup and world championship events. To investigate the effects of rear suspension systems, a rig was designed on which two mountain bicycles were tested, one with (SU) and one without (HT) a rear suspension system. The purpose of this rig was to isolate the effects of rear wheel impact in order to conduct comparative performance tests of the bicycles with a number of cyclists. The rig held the front forks of the bicycle under test vertical and stationary while the rear wheel travelled on a large diameter roller. 'No bump' tests were conducted with the roller covered by carpet and with a drag load provided by a friction belt, while for the 'bump' tests wooden strips were attached across the surface of the roller and the friction belt was removed. Subjects, aged 22.3 +/-2.54 years, performed bump and no bump tests with both bicycles under sub-maximal conditions. The physiological and psychological effects on cyclists riding the two types of bicycle on the simulated track of the rig were measured by the cyclists' oxygen consumption (VO2), heart rate, RPE (Borg 6-20 scale), and comfort (scale 1-5) rating. The dynamic behaviour of the bicycles was also observed by measuring the vertical acceleration of the saddle and handlebars, the chain tension, tangential crank velocity at the pedals, the force applied to the front mounting braclcet and the tangential surface velocity of the roller. A DADS model of the bicycle/rider dynamics was developed and the results from this model were compared with the measured dynamic behaviour of the two bicycles. Results from the bump tests show a significant advantage for the SU bicycle over the HT bicycle in oxygen consumption (9.14 ml -- kg-1--min-1, P < 0.001), heart rate (34.43 beats -- min-1, P < 0.001), energy expenditure (14.43 KJ-- min-1), RPE (1.83, P < 0.05), comfort (1.87, P < 0.001), maximum saddle and handle bar acceleration (1.45 and 0.54 g's respectively) and displacement (11.8 and 7.5 mm respectively), maximum and mean pedal force (122 and 59 N respectively) and mean pedal power output (64 Watts), and the horizontal force of bump impact measured at the front mounting bracket (197 N). During the no bump test there was a small (2.18 ml o kg-1 o min-1 and 2.97 KJ o min-1 respectively) but significant (P < 0.005 and P < 0.025 respectively) increase in oxygen consumption and energy expenditure of the subject on the SU bicycle but no significant difference between the bicycles in the heart rate, RPE or comfort of the subject. There was a significant (P < 0.025 and P < 0.05 respectively) but small increase in the maximum and mean pedal force (34 and 16 N respectively) and mean pedal power output (14 Watts, P < 0.025) for the HT bicycle. There was no significant difference between the other mechanical values. The physiological, psychological, mechanical and simulation results correlated well for the bump test. The results from the rig simulation confirmed that energy was lost from each bump impact and proved a useful tool in the analysis of the mechanical results, with which they correlated well. The physiological and mechanical results show that the SU bicycle offers significant advantages over the HT bicycle during the bump test. The results for the no bump test do not correlate for some variables, but the differences are very small between the two bicycles

Targeted AntiBiotics for Chronic pulmonary diseases (TARGET ABC):can targeted antibiotic therapy improve the prognosis of Pseudomonas aeruginosa-infected patients with chronic pulmonary obstructive disease, non-cystic fibrosis bronchiectasis, and asthma? A multicenter, randomized, controlled, open-label trial

BACKGROUND: Pseudomonas aeruginosa infection is seen in chronic pulmonary disease and is associated with exacerbations and poor long-term prognosis. However, evidence-based guidelines for the management and treatment of P. aeruginosa infection in chronic, non-cystic fibrosis (CF) pulmonary disease are lacking. The aim of this study is to investigate whether targeted antibiotic treatment against P. aeruginosa can reduce exacerbations and mortality in patients with chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis, and asthma. METHODS: This study is an ongoing multicenter, randomized, controlled, open-label trial. A total of 150 patients with COPD, non-CF bronchiectasis or asthma, and P. aeruginosa-positive lower respiratory tract samples will be randomly assigned with a 1:1 ratio to either no antibiotic treatment or anti-pseudomonal antibiotic treatment with intravenous beta-lactam and oral ciprofloxacin for 14 days. The primary outcome, analyzed with two co-primary endpoints, is (i) time to prednisolone and/or antibiotic requiring exacerbation or death, in the primary or secondary health sector, within days 20–365 from study allocation and (ii) days alive and without exacerbation within days 20–365 from the study allocation. DISCUSSION: This trial will determine whether targeted antibiotics can benefit future patients with chronic, non-CF pulmonary disease and P. aeruginosa infection in terms of reduced morbidity and mortality, thus optimizing therapeutic approaches in this large group of chronic patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT03262142. Registered on August 25, 2017. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06720-z