Criterion validity and reliability of a smartphone delivered sub-maximal fitness test for people with type 2 diabetes

Abstract

BackgroundPrevention of multi-morbidities following non-communicable diseases requires a systematic registration of adverse modifiable risk factors, including low physical fitness. The aim of the study was to establish criterion validity and reliability of a smartphone app (InterWalk) delivered fitness test in patients with type 2 diabetes.MethodsPatients with type 2 diabetes (N = 27, mean (SD) age 64.2 (5.9) years, BMI 30.0 (5.1) kg/m2, (30 % male)) completed a 7-min progressive walking protocol twice (with and without encouragement). VO2 during the test was assessed using indirect calorimetry and the acceleration (vector magnitude) from the smartphone was obtained. The vector magnitude was used to predict VO2peak along with the co-variates weight, height and sex. The validity of the algorithm was tested when the smartphone was placed in the right pocket of the pants or jacket. The algorithm was validated using leave-one-out cross validation. Test-retest reliability was tested in a subset of participants (N = 10).ResultsThe overall VO2peak prediction of the algorithm (R2) was 0.60 and 0.45 when the smartphone was placed in the pockets of the pants and jacket, respectively (p < 0.001). The mean bias (limits of agreement) in the cross validation was−0.4 (38) % (pants) and−0.1 (46) % (jacket). When the smartphone was placed in the jacket a significant intensity dependent bias (r = 0.5, p = 0.02) was observed. The test-retest intraclass correlations were 0.85 and 0.86 (p < 0.001), for the pants and jacket, respectively. No effects of encouragement were observed on test performance.ConclusionIn conclusion, the InterWalk Fitness Test is accurate and reliable for persons with type 2 diabetes when the smartphone is placed in the side pocket of the pants for. The test could give a fair estimate of the CRF in absence of a progressive maximal test during standardized conditions with the appropriate equipment.Trial registration www.clinicaltrials.org (NCT02089477), first registered (prospectively) on March 14th 2014

Resting Metabolic Rate Does Not Change in Response to Different Types of Training in Subjects with Type 2 Diabetes

“…Exclusion criteria were pregnancy, smoking, contraindication to increased levels of physical activity (26), insulin dependence, and evidence of thyroid, liver, lung, heart, or kidney disease. All subjects underwent a screening consisting of a medical interview and examination, an oral glucose tolerance test (OGTT), a walking VO 2 peak test with indirect calorimetry (Cosmed K4B2, Rome, Italy) and a familiarization VO 2 max test performed on a treadmill (Katana Sport, Lode, Groningen, the Netherlands) with indirect calorimetry (Cosmed Quark, Rome, Italy) as previously described (22, 27). Written and informed consent was obtained from all research participants before any investigations were performed and the studies were approved by the Ethical Committee of the Capital Region of Denmark (H-6-2014-043 and H-1-2013-116) and registered at (NCT02320526) and (NCT02089477).…”

Long-term effect of smartphone-delivered Interval Walking Training on physical activity in patients with type 2 diabetes: protocol for a parallel group single-blinded randomised controlled trial

“…IWT is personalised through a standardised 8 minute walking test, performed with the app before engaging in IWT. 24 The InterWalk app guides the user in IWT with repeated cycles of 3 min fast and 3 min slow walking. During IWT, the InterWalk app provides the patient with continuous feedback on the walking speed.…”

“…Additionally, a monitor is fixed on the lateral side of the right thigh (Leukomed T, BSN medical, Germany) for supporting information about posture. 24 The patients are instructed not to remove the PA monitor at any time during the three time periods. If de-attached, the participants are trained in fixing the monitors correctly and are instructed to note the incident.…”

“…The four paces are self-selected (see figures 3 and 4 ). 24 The test is performed with an iPod placed in the pocket at the hip and the instructions are delivered from the app through earphones. To ensure the right walking intensity in the intervention period, the patients are asked to perform the test every fourth week.…”

Protocol for the specialist supervised individualised multifactorial treatment of new clinically diagnosed type 2 diabetes in general practice (IDA): a prospective controlled multicentre open-label intervention study

“…Following each training session, the app sends the data to a central server. 49 The training data will be available for the patient and the healthcare professionals making it possible to provide evidence-based training feedback to patients, using physical fitness data, 50 training duration and compliance from the app. 49 The InterWalk app will be implemented in the Liva platform.…”