Performance and perceived fatigability across the intensity spectrum: Role of muscle mass during cycling.

INTRODUCTION: The role of muscle mass in modulating performance and perceived fatigability across the entire intensity spectrum during cycling remains unexplored. We hypothesized that at task failure (Tlim), muscle contractile function would decline more following single- (SL) vs. double-leg (DL) cycling within severe- and extreme-, but not moderate- and heavy-, intensities. METHODS: Following DL and SL ramp-incremental tests, on separate days, eleven recreationally active males (V̇O2max: 49.5±7.7mL·kg-1·min-1) completed SL and DL cycling until Tlim within each intensity domain. Power output for SL trials was set at 60% of the corresponding DL trial. Prior to and immediately after Tlim, participants performed an isometric maximal voluntary contraction (MVC) coupled with one superimposed and three resting femoral nerve stimulations (100Hz; 10Hz; single twitch (Qtw)) to measure performance fatigability. Perceived fatigue, leg pain, dyspnea, and effort were collected during trials. RESULTS: Tlim within each intensity domain was not different between SL and DL (all P>0.05). MVC declined more for SL vs. DL following heavy- (-42±16% vs. -30±18%; P=0.011) and severe-intensity cycling (-41±12% vs. -31±15%; P=0.036). Similarly, peak Qtw force declined more for SL following heavy- (-31±12% vs. -22±10%; P=0.007) and severe-intensity cycling (-49±13% vs. -40±7%; P=0.048). Except for heavy-intensity, voluntary activation reductions were similar between modes. Similarly, except for dyspnea, which was lower for SL vs. DL across all domains, ratings of fatigue, pain, and effort were similar at Tlim between exercise modes. CONCLUSIONS: Thus, the amount of muscle mass modulates the extent of contractile function impairment in an intensity-dependant manner.

Methodological considerations on near-infrared spectroscopy derived muscle oxidative capacity.

PURPOSE: Different strategies for near-infrared spectroscopy (NIRS)-derived muscle oxidative capacity assessment have been reported. This study compared and evaluated (I) approaches for averaging trials; (II) NIRS signals and blood volume correction equations; (III) the assessment of vastus lateralis (VL) and tibialis anterior (TA) muscles in two fitness levels groups. METHODS: Thirty-six participants [18 chronically trained (CT: 14 males, 4 females) and 18 untrained (UT: 10 males, 8 females)] participated in this study. Two trials of twenty transient arterial occlusions were performed for NIRS-derived muscle oxidative capacity assessment. Muscle oxygen consumption ([Formula: see text]O2m) was estimated from deoxygenated hemoglobin (HHb), corrected for blood volume changes following Ryan (HHbR) and Beever (HHbB) equations, and from oxygen saturation (StO2) in VL and TA. RESULTS: Superimposing or averaging [Formula: see text]O2m or averaging the rate constants (k) from the two trials resulted in equivalent k values [two one-sided tests (TOST) procedure with 5% equivalence margin-P < 0.001]. Whereas HHbR (2.35 ± 0.61 min-1) and HHbB (2.34 ± 0.58 min-1) derived k were equivalent (P < 0.001), StO2 derived k (2.81 ± 0.92 min-1) was greater (P < 0.001) than both. k values were greater in CT vs UT in both muscles (VL: + 0.68 min-1, P = 0.002; TA: + 0.43 min-1, P = 0.01). CONCLUSION: Different approaches for averaging trials lead to similar k. HHb and StO2 signals provided different k, although different blood volume corrections did not impact k. Group differences in k were detected in both muscles.

Heavy-, Severe-, and Extreme-, but not Moderate-Intensity Exercise Increase V̇o2max and Thresholds after 6 Weeks of Training.

INTRODUCTION: This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O2max) and submaximal thresholds. METHODS: Eighty-four young healthy participants (42 Females, 42 Males) were randomly assigned to six age, sex, and V̇O2max-matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD)-, 2) lower heavy (HVY1)-, and 3) upper heavy-intensity (HVY2)- domain; interval cycling, in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for, 6) control (CON). All training groups except SIT, were work-matched. Training participants completed three sessions per week for six weeks with physiological evaluations performed at PRE, MID and POST intervention. RESULTS: Compared to the change in V̇O2max (∆V̇O2max) in CON (0.1 ± 1.2 mL·kg-1·min-1), all training groups except MOD (1.8 ± 2.7 mL·kg-1·min-1), demonstrated a significant increase (p < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL·kg-1·min-1) followed by HVY2 (5.4 ± 2.3 mL·kg-1·min-1), SIT (4.7 ± 2.3 mL·kg-1·min-1), and HVY1 (3.3 ± 2.4 mL·kg-1·min-1), respectively. The Δ PO at the estimated lactate threshold (θLT) was similar across HVY1, HVY2, HIIT and SIT which were all greater than CON (p < 0.05). The Δ V̇O2 and Δ PO at θLT for MOD was not different from CON (p > 0.05). HIIT produced the highest Δ PO at maximal metabolic steady state, which was greater than CON, MOD, and SIT (p < 0.05). CONCLUSIONS: This study demonstrated that i) exercise intensity is a key component determining changes in V̇O2max and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals.

A Ramp versus Step Transition to Constant Work Rate Exercise Decreases Steady-State Oxygen Uptake.

PURPOSE: This study aimed to investigate whether a ramp-to-constant WR (rCWR) transition compared with a square-wave-to-constant WR (CWR) transition within the heavy-intensity domain can reduce metabolic instability and decrease the oxygen cost of exercise. METHODS: Fourteen individuals performed (i) a ramp-incremental test to task failure, (ii) a 21-min CWR within the heavy-intensity domain, and (iii) an rCWR to the same WR. Oxygen uptake (V̇O 2 ), lactate concentration ([La - ]), and muscle oxygen saturation (SmO 2 ) were measured. V̇O 2 and V̇O 2 gain (V̇O 2 -G) during the first 10-min steady-state V̇O 2 were analyzed. [La - ] before, at, and after steady-state V̇O 2 and SmO 2 during the entire 21-min steady-state exercise were also examined. RESULTS: V̇O 2 and V̇O 2 -G during rCWR (2.49 ± 0.58 L·min -1 and 10.7 ± 0.2 mL·min -1 ·W -1 , respectively) were lower ( P < 0.001) than CWR (2.57 ± 0.60 L·min -1 and 11.3 ± 0.2 mL·min -1 ·W -1 , respectively). [La - ] before and at steady-state V̇O 2 during the rCWR condition (1.94 ± 0.60 and 3.52 ± 1.19 mM, respectively) was lower than the CWR condition (3.05 ± 0.82 and 4.15 ± 1.25 mM, respectively) ( P < 0.001). [La - ] dynamics after steady-state V̇O 2 were unstable for the rCWR ( P = 0.011). SmO 2 was unstable within the CWR condition from minutes 4 to 13 ( P < 0.05). CONCLUSIONS: The metabolic disruption caused by the initial minutes of square-wave exercise transitions is a primary contributor to metabolic instability, leading to an increased V̇O 2 -G compared with the rCWR condition approach. The reduced early reliance on anaerobic energy sources during the rCWR condition may be responsible for the lower V̇O 2 -G.

Evaluation of ocular surface following PreserFlo Microshunt implantation: Functional outcomes and quality of life.

BACKGROUND: This study aimed to evaluate the impact of PreserFlo Microshunt on the ocular surface, focusing on both objective and subjective parameters. METHODS: Prospective-observational study on 48 eyes undergoing PreserFlo Microshunt implantation, standalone or combined with phacoemulsification. At baseline, 1-month, 6-months and 12-months post-operative follow-ups, we performed Ocular Surface Disease Index (OSDI) questionnaire, Schirmer's test (ST), Tear-film break-up time (TBUT), fluoresceine staining (FS), tear osmolarity and minimum corneal epithelial thickness (Epi-ThkMIN. ) measurements. RESULTS: OSDI score improved from 37.43 ± 17.49 at baseline, to 24.13 ± 12.55 at 1-month (p = 0.003) and to 12.89 ± 8.54 and 13.09 ± 10.22 at 6-months and 12-months (p < 0.0001). TBUT and ST, in a similar way, non-significantly increased at 1-month, but then improved at 6-months and 12-months (p < 0.05 for both). Tear osmolarity significantly decreased from 308.2 ± 7.3 mOsm/L at baseline, to 303.3 ± 8.2 mOsm/L, 295.6.2 ± 7.0 mOsm/L and 297.6 ± 6.8 mOsm/L at 1-month, 6-months and 12-months (p < 0.05 for all). Epi-ThkMIN was stable when comparing baseline (44.9 ± 5.7 µm) and 1-month (p = 0.28), and successively increased in 6-months (47.8 ± 5.5 µm, p = 0.02) and 12-months (48.0 ± 3.6 µm, p = 0.01). In subgroup analysis, OSDI score and tear osmolarity were significantly higher at 1-month in combined group compared to standalone group (p = 0.03 and p = 0.02, respectively), but reaching comparable values in successive follow-ups. Further, Oxford scale grades for FS were significantly improved when comparing baseline-6-months and baseline-12-months. CONCLUSION: PreserFlo implantation improved ocular surface subjective symptoms, increased TBUT and ST, and reduced FS, highlighting the potential benefits of this surgical intervention. Moreover, we reported significant improvements of tear osmolarity and corneal epithelium.

Epiretinal implant of human amniotic membrane to treat highly myopic macular hole retinal detachments: A novel surgical technique.

PURPOSE: To describe a new surgical technique involving the use of a human amniotic membrane (hAM) epiretinal patch to treat a primary macular hole retinal detachment (MHRD) in a highly myopic patient. METHODS: A 60 years old highly myopic man was referred to our clinic with a diagnosis of MHRD in his right eye. The patient was pseudophakic, with a visual acuity of counting fingers at the baseline evaluation. Pars plana vitrectomy was performed, a small retinotomy was created at the inner margin of the staphyloma, and membrane blue dual was used to obtain an adequate peeling of the inner limiting membrane. Then, a 1.5 mm diameter circular hAM patch was obtained and positioned over the macular hole with the chorion layer settled over the retina. After a complete fluid-air exchange, 20% sulfur hexafluoride gas was used as endotamponade, and the patient was asked to remain face down for three days. RESULTS: Four weeks after surgery, optical coherence tomography (OCT) scan showed the hAM patch, visualized as a distinct hyperreflective layer well integrated with the retina. Nine months after surgery, the macular hole was closed, the retina reattached, the hAM patch was adherent to the retina, and the patient presented a best-corrected visual acuity improved to 0.7 logMar. No postoperative adverse events were registered during the follow-up. CONCLUSIONS: Epiretinal hAM implant could represent a novel surgical technique, feasible and easier compared to other current techniques used to treat MHRD in highly myopic patients.

Evaluation of the "Step-Ramp-Step" Protocol: Accurate Aerobic Exercise Prescription with Different Steps and Ramp Slopes.

PURPOSE: To assess whether: i) a lower amplitude constant-load MOD is appropriate to determine the mean response time (MRT); ii) the method accurately corrects the dissociation in the V̇O 2 -PO relationship during ramp compared with constant-load exercise when using different ramp slopes. METHODS: Eighteen participants (7 females) performed three SRS tests including: i) step-transitions into MOD from 20 to 50 W (MOD 50 ) and 80 W (MOD 80 ); and ii) slopes of 15, 30, and 45 W·min -1 . The V̇O 2 and PO at the gas exchange threshold (GET) and the corrected respiratory compensation point (RCP CORR ) were determined. Two to three 30-min constant-load trials evaluated the V̇O 2 and PO at the maximal metabolic steady state (MMSS). RESULTS: There were no differences in V̇O 2 at GET (1.97 ± 0.36, 1.99 ± 0.36, 1.95 ± 0.30 L·min -1 ), and RCP (2.81 ± 0.57, 2.86 ± 0.59, 2.84 ± 0.59) between 15, 30, and 45 W·min -1 ramps, respectively ( P > 0.05). The MRT in seconds was not affected by the amplitude of the MOD or the slope of the ramp (range 19 ± 10 s to 23 ± 20 s; P > 0.05). The mean PO at GET was not significantly affected by the amplitude of the MOD or the slope of the ramp (range 130 ± 30 W to 137 ± 30 W; P > 0.05). The PO at RCP CORR was similar for all conditions ((range 186 ± 43 W to 193 ± 47 W; P > 0.05). CONCLUSIONS: The SRS protocol accounts for the V̇O 2 MRT when using smaller amplitude steps, and for the V̇O 2 slow component when using different ramp slopes, allowing for accurate partitioning of the exercise intensity domains in a single test.

Suprachoroidal Hemorrhage.

Suprachoroidal hemorrhage (SCH) refers to the accumulation of blood in the suprachoroidal space, a relatively uncommon but significant complication that can occur spontaneously, during ophthalmic surgery, or as a consequence of ocular trauma. If left undiagnosed and untreated, SCH can lead to severe vision loss or even blindness. Therefore, it is crucial for ophthalmologists to have a thorough understanding of this complication, taking proactive measures to prevent it during surgery and being knowledgeable about effective management strategies for patients with SCH. This review article aimed to provide a comprehensive overview of SCH, covering its risk factors, diagnostic approaches, and the best practices for its management. By enhancing awareness and knowledge in this area, we can improve patient outcomes and minimize the impact of SCH in ophthalmic practice.

Can the heart rate response at the respiratory compensation point be used to retrieve the maximal metabolic steady state?

The metabolic rate (VO2) at the maximal metabolic steady state (MMSS) is generally not different from the VO2 at the respiratory compensation point (RCP). Based on this, it is often assumed that the heart rate (HR) at RCP would also be similar to that at MMSS. The study aims to compare the HR at RCP with that at MMSS. Seventeen individuals completed a ramp-incremental test, a series of severe-intensity trials to estimate critical power and two-to-three 30-min trials to confirm MMSS. The HR at RCP was retrieved by linear interpolation of the ramp-VO2/HR relationship and compared to the HR at MMSS recorded at 10, 15, 20, 25 and 30 min. The HR at RCP was 166 ± 12 bpm. The HR during MMSS at the timepoints of interest was 168 ± 8, 171 ± 8, 175 ± 9, 177 ± 9 and 178 ± 10 bpm. The HR at RCP was not different from the HR at MMSS at 10 min (P > 0.05) but lower at subsequent timepoints (P < 0.05) with this difference becoming progressively larger. For all timepoints, limits of agreement were large (~30 bpm). Given these differences and the variability at the individual level, the HR at RCP cannot be used to control the metabolic stimulus of endurance exercise.

FIL SSF intraocular lens opacification after pars plana vitrectomy with gas tamponade for traumatic lens luxation and retinal detachment: a case report and literature review.

BACKGROUND: To report a case of sutureless scleral-fixated hydrophilic intraocular lens (FIL SSF IOL, Soleko, Italy) opacification following pars plana vitrectomy surgery using sulfur hexafluoride (SF6) for traumatic lens luxation associated with retinal detachment. CASE PRESENTATION: A 77-year-old woman was referred to our emergency department after blunt trauma in her right eye. At the ophthalmic evaluation, visual acuity was hand movement, biomicroscopy showed pseudoexfoliation syndrome and a traumatic lens luxation in the vitreous chamber. The patient underwent pars plana vitrectomy, subluxated cataract explantation, and FIL SSF IOL implant. During surgery, an inferior retinal detachment was encountered, requiring 20% SF6 gas tamponade. No adverse events were encountered. One month postoperatively, visual acuity (BCVA) improved to 0,3 logMAR. At the 3-month follow-up, the patient presented with BCVA of 0,5 logMAR, and biomicroscopy showed a minimal IOL opacification. Six months postoperatively, BCVA decreased to 1.0 logMAR, and diffuse, IOL opacification was noted at slit lamp examination. The patient refused any other surgical intervention for IOL exchange. CONCLUSIONS: Although hydrophilic IOL opacification gas related is known, to the best of our knowledge, this is the first case reported in the literature of FIL SSF IOL opacification after pars plana vitrectomy with gas tamponade for retinal detachment.

Long-term functional and structural outcomes after large chorioretinectomy for ruptured globe following blunt trauma.

BACKGROUND: The purpose of this study was to present a modified surgical technique involving pars plana vitrectomy with large chorioretinectomy for eyes with rupture of the globe due to severe ocular blunt trauma. METHODS: This retrospective study included consecutive patients with rupture of the globe due to blunt trauma who were treated at the King Khaled Eye Specialist Hospital (Riyadh, Saudi Arabia). All patients underwent 25-gauge pars plana vitrectomy with large chorioretinectomies involving all the tissue around the posterior scleral wounds. Outcome measures included best-corrected visual acuity (BCVA), anatomical success and globe survival, rates of complications. RESULTS: 15 eyes of 15 patients were included. Mean BCVA was 2.88 ± 0.13 logMAR at presentation, and significantly improved to 0.83 ± 0.28 logMAR (P < 0.001), with 10 patients (67%) achieving a final BCVA ≥ 20/200. Anatomical success and globe survival were achieved in 11 (73%) and 15 (100%) of eyes, respectively. Postoperative complications included retinal detachment in 6 eyes (40%), epiretinal membrane in 6 (40%), hypotony in 4 (26%), PVR in 2 (13%). CONCLUSIONS: Pars plana vitrectomy with large chorioretinectomy is an effective treatment for globe rupture following severe blunt trauma, yielding good visual outcomes and anatomical success rates.

Recent developments in imaging and surgical vision technologies currently available for improving vitreoretinal surgery: a narrative review.

INTRODUCTION: Recent technologies and new devices continue to be developed in vitreoretinal surgeries, and they provide more details, enhance safety, improve surgeons' comfort, and better visual and anatomical outcomes. Some devices have been used for better visualization during surgery, and some help the operation performance. They are divided into the following titles: Intraoperative OCT (including hand-held, probe-integrated, and microscope-integrated OCT), three-dimensional visualization system, virtual reality system, endoscopic vitrectomy (fiber optics and non-fiber optics), wide-angle viewing systems (contact and non-contact lenses), endo-illumination, light filters, chromovitrectomy, the retinal prosthesis (including epiretinal, subretinal, and suprachoroidal devices), robot-assisted vitreoretinal surgery, newer Vitreoretinal instruments, gene and cell therapy. AREAS COVERED: In this narrative review, we focused on PubMed articles between 2010-2023 with these keywords: 'Optical Coherence Tomography,' 'Three-Dimensional,' 'Virtual System,' 'intraoperative,' 'endoscopic,' 'vitrectomy,' 'lens,' 'illumination,' 'filters,' 'chromovitrectomy,' 'prosthesis,' 'robotic surgery,' 'instrument,' 'gene,' 'cell.' EXPERT OPINION: The main aim of this review is to update the reader on the latest progression in intraoperative imaging and surgical vision technologies and to provide an understanding of how each has helped improve operation and surgical outcomes. The surgeons should know recent updates to do their best and achieve the most excellent results.

A Single Test Protocol to Establish the Full Spectrum of Exercise Intensity Prescription.

PURPOSE: We aimed to test the extended capabilities of the SRS protocol by validating its capacity to predict the power outputs for targeted metabolic rates (V̇O 2 ) and time-to-task failure ( Tlim ) within the heavy- and severe-intensity domain, respectively. METHODS: Fourteen young individuals completed (i) an SRS protocol from which the power outputs at GET and RCP (RCP CORR ), and the work accruable above RCP CORR , defined as W ' RAMP , were derived; (ii) one heavy-intensity bout at a power output predicted to elicit a targeted V̇O 2 equidistant from GET and RCP; and (iii) four severe-intensity trials at power outputs predicted to elicit targeted Tlim at minutes 2.5, 5, 10, and 13. These severe-intensity trials were also used to compute the constant-load-derived critical power and W ´ ( W ' CONSTANT ). RESULTS: Targeted (2.41 ± 0.52 L·min -1 ) and measured (2.43 ± 0.52 L·min -1 ) V̇O 2 at the identified heavy-intensity power output (162 ± 43 W) were not different ( P = 0.71) and substantially concordant (CCC = 0.95). Likewise, targeted and measured Tlim for the four identified severe-intensity power outputs were not different ( P > 0.05), and the aggregated coefficient of variation was 10.7% ± 8.9%. The derived power outputs at RCP CORR (192 ± 53 W) and critical power (193 ± 53 W) were not different ( P = 0.65) and highly concordant (CCC = 0.99). There were also no differences between W ' RAMP and W ' CONSTANT ( P = 0.51). CONCLUSIONS: The SRS protocol can accurately predict power outputs to elicit discrete metabolic rates and exercise durations, thus providing, with time efficiency, a high precision for the control of the metabolic stimulus during exercise.

Double-flanged knotless technique for iris prosthesis and IOL implantation associated with keratoplasty.

INTRODUCTION: Anterior segment reconstruction and penetrating keratoplasty combined with iris prosthesis (IP) and intraocular lens (IOL) scleral fixation require prolonged open-sky surgery and complex suturing. Herein we present a novel double-flanged knotless surgical technique that minimizes the open sky duration and facilitates the fixation of the IP and IOL complex to the sclera. METHODS: After corneal trephination and removal, a temporary keratoprosthesis is fixated. Three 5.0 polypropylene suture segments are introduced in the anterior chamber transconjunctivally and then externalized through keratoprosthesis. Each suture is threaded through the eyelets of the IP and then flanged. The temporary keratoprosthesis is removed, and the IP and IOL complex is positioned in the sulcus. A donor cornea button is sutured in place and the IP is centred on the optical axis by adjusting the polypropylene sutures. Finally, the suture ends are shortened, flanged, and buried under the conjunctiva. RESULTS: Surgery was performed on three eyes of three patients. No intraoperative complications occurred, while cystoid macular edema and ocular hypertension occurred in two patients during the follow-up period. The best corrected visual acuity was 6/20, 8/20, and 13/20. So far the IPs remained stable in the three eyes with a maximum follow-up of 18 months. CONCLUSION: This novel technique of penetrating keratoplasty combined with an intraocular lens (IOL) and iris prosthesis implantation makes it possible to reduce open sky surgery time, avoid complex suturing, and ensure optimal IOL visual axis alignment by adjusting suture tension.

Intraoperative OCT for Lamellar Corneal Surgery: A User Guide.

Intraoperative OCT is an innovative and promising technology which allows anterior and posterior segment ocular surgeons to obtain a near-histologic cross-sectional and tomographic image of the tissues. Intraoperative OCT has several applications in ocular surgery which are particularly interesting in the context of corneal transplantation. Indeed, iOCT images provide a direct and meticulous visualization of the anatomy, which could guide surgical decisions. In particular, during both big-bubble and manual DALK, the visualization of the relationship between the corneal layers and instruments allows the surgeon to obtain a more desirable depth of the trephination, thus achieving more type 1 bubbles, better regularity of the plane, and a reduced risk of DM perforation. During EK procedures, iOCT supplies information about proper descemetorhexis, graft orientation, and interface quality in order to optimize the postoperative adhesion and reduce the need for re-bubbling. Finally, mushroom PK, a challenging technique for many surgeons, can be aided through the use of iOCT since it guides the correct apposition of the lamellae and their centration. The technology of iOCT is still evolving: a larger field of view could allow for the visualization of all surgical fields, and automated tracking and iOCT autofocusing guarantee the continued centration of the image.

Different ramp-incremental slopes elicit similar V̇o2max and fatigability profiles in females and males despite differences in peak power output.

The aim of this article is to investigate the effects of different ramp-incremental (RI) slopes on fatigability and its recovery in females and males. Ten females and 11 males performed RI tests with distinct slopes, in separated and randomized sessions, 15 (RI15), 30 (RI30), and 45 (RI45) W·min-1. Performance fatigability was assessed by femoral nerve electrical stimuli evoked during and after isometric maximal voluntary contraction (IMVC) of knee extensors at baseline and after task failure at min 0.5, 1.5, 2.5, 5, and 10. Maximal oxygen uptake (V̇o2max) and peak power output (POpeak) were also measured. There were significant and similar declines from pre- to post-RI test in RI15, RI30, and RI45 for IMVC (-23%; -25%; -25%, respectively; P < 0.05) and potentiated single twitch (-46%; -47%; -49%; P < 0.05), whereas voluntary activation did not change (-1%; -1%; 0%; P > 0.05). There were no RI condition effects, nor time × condition interaction for IMVC, potentiated single twitch and voluntary activation (all P > 0.05). V̇o2max was not different among RI15, RI30, and RI45 conditions (3.30, 3.29, and 3.26 L·min-1, respectively; P = 0.717), but POpeak was (272, 304, and 337 W, respectively; P < 0.001). Overall, performance fatigability profiles were similar between sexes after the RI tests and during recovery. In addition, during recovery, high-frequency doublets and single twitch recovered faster after RI30 and RI45 compared with RI15, regardless of sex (all P > 0.05 for sex differences). In conclusion, RI tests of different slopes that elicited similar V̇o2max but different POpeak did not affect the profile of performance fatigability at task failure in females and males.NEW & NOTEWORTHY It was unknown whether performance fatigability and its recovery are affected by different slopes in a ramp incremental (RI) test. It was also uncertain if females and males would respond differently. Performance fatigability was the same regardless of the RI slope adopted and the sex of the population, which was accompanied by similar maximal oxygen uptake but different power output achieved. The recovery of contractile function was similar between sexes but delayed after slower RI slopes.

An evaluation of the role of the exercise training dose for changes in exercise capacity following a standard cardiac rehabilitation program.

BACKGROUND: To retrospectively characterize and compare the dose of exercise training (ET) within a large cohort of patients demonstrating different levels of improvement in exercise capacity following a cardiac rehabilitation (CR) program. METHODS: A total of 2310 patients who completed a 12-week, center-based, guidelines-informed CR program between January 2018 and December 2019 were included in the analysis. Peak metabolic equivalents (METpeak) were determined pre- and post-CR during which total duration (ET time) and intensity [percent of heart rate peak (%HRpeak)] of supervised ET were also obtained. Training responsiveness was quantified on the basis of changes in METpeak from pre- to post-CR. A cluster analysis was performed to identity clusters demonstrating discrete levels of responsiveness (i.e., negative, low, moderate, high, and very-high). These were compared for several baseline and ET-derived variables which were also included in a multivariable linear regression model. RESULTS: At pre-CR, baseline METpeak was progressively lower with greater training responsiveness (F(4,2305) = 44.2, P < 0.01, η2p = 0.71). Likewise, average training duration (F(4,2305) = 10.7 P < 0.01, η2p = 0.02) and %HRpeak (F(4,2305) = 25.1 P < 0.01, η2p = 0.042) quantified during onsite ET sessions were progressively greater with greater training responsiveness. The multivariable linear regression model confirmed that baseline METpeak, training duration and intensity during ET, BMI, and age (P < 0.001) were significant predictors of METpeak post-CR. CONCLUSIONS: Along with baseline METpeak, delta BMI, and age, the dose of ET (i.e., training duration and intensity) predicts METpeak at the conclusion of CR. A re-evaluation of current approaches for exercise intensity prescription is recommended to extend the benefits of completing CR to all patients.

Shorter High-Intensity Cycling Intervals Reduce Performance and Perceived Fatigability at Work-Matched but Not Task Failure.

INTRODUCTION: The intensity, duration, and distribution of work and recovery phases during high-intensity interval training (HIIT) modulate metabolic perturbations during exercise and subsequently influence the development of performance fatigability and exercise tolerance. This study aimed to characterize neuromuscular, perceptual, and cardiorespiratory responses to work-to-rest ratio-matched HIIT protocols differing in work and rest interval duration. METHODS: Twelve healthy individuals (six women) first completed a ramp incremental test to determine 90% of peak power output, and then in three randomized visits, they completed three cycling protocols to task failure at 90% of peak power output: (i) 3- to 3-min work-to-passive rest ratio HIIT (HIIT 3min ), (ii) 1- to 1-min work-to-passive rest ratio HIIT (HIIT 1min ), and (iii) constant load (CL). Interpolated twitch technique, including maximal voluntary isometric knee extensions and femoral nerve electrical stimuli, was performed at baseline, every 6 min of work, and task failure. Perceptual and cardiorespiratory responses were recorded every 3 min and continuously across the exercises, respectively. RESULTS: The work completed during HIIT 1min (8447 ± 5124 kJ) was considerably greater than HIIT 3min (1930 ± 712 kJ) and CL (1076 ± 356) ( P < 0.001). At work-matched, HIIT 1min resulted in a lesser decline in maximal voluntary contraction and twitch force compared with HIIT 3min and CL ( P < 0.001). Perceived effort, pain, and dyspnea were least in HIIT 1min and HIIT 3min compared with CL ( P < 0.001). At task failure, HIIT 1min resulted in less voluntary activation than HIIT 3min ( P = 0.010) and CL ( P = 0.043), and engendered less twitch force decline than CL ( P = 0.021). CONCLUSIONS: Overall, the mitigated physiological and perceptual responses during shorter work periods (HIIT 1min ) enhance exercise tolerance in comparison to longer work intervals at the same intensity (HIIT 3min , CL).

Human glial müller and umbilical vein endothelial cell coculture as an in vitro model to investigate retinal oxidative damage. A morphological and molecular assessment.

The aim of this study was to optimize a coculture in vitro model established between the human Müller glial cells and human umbilical vein endothelial cells, mimicking the inner blood-retinal barrier, and to explore its resistance to damage induced by oxidative stress. A spontaneously immortalized human Müller cell line MIO-M1 and human umbilical vein endothelial cells (HUVEC) were plated together at a density ratio 1:1 and maintained up to the 8th passage (p8). The MIO-M1/HUVECs p1 through p8 were treated with increasing concentrations (range 200-800 µM) of H2 O2 to evaluate oxidative stress induced damage and comparing data with single cell cultures. The following features were assayed p1 through p8: doubling time maintenance, cell viability using MTS assay, ultrastructure of cell-cell contacts, immunofluorescence for Vimentin and GFAP, molecular biology (q-PCR) for GFAP and CD31 mRNA. MIO-M1/HUVECs cocultures maintained distinct cell cytotype up to p8 as shown by flow cytometry analysis, without evidence of cross activation, displaying cell-cell tight junctions mimicking those found in human retina, only acquiring a slight resistance to oxidative stress induction over the passages. This MIO-M1/HUVECs coculture represents a simple, reproducible and affordable model for in vitro studies on oxidative stress-induced retinal damages.