Respiratory Threshold as A New Threshold Determination Method based on Respiratory Responses and It’s Success to Indicate Critical Power

Öz

The respiratory threshold (RT), introduced as a new threshold determination method that relied on respiratory responses, is based on the analysis of time-dependent changes in the value of minute ventilation divided by the end-tidal partial pressure of CO2 (VE/PETCO2) in an incremental ramp test. However, there is no research finding focusing on the level at which the RT technique can indicate the critical power (CP), which is an essential threshold determination method widely used. The aim of this study was to investigate at which level the exercise intensity obtained using the RT technique can meet the CP. Ten well-trained male cyclists participated in the study. Gas exchange threshold (GET), respiratory compensation point (RCP), and RT levels of the athletes were determined by incremental ramp tests. In those tests, GET and RCP were evaluated by detecting breakpoints obtained in relationships of VCO2-VO2 and VE-VCO2 using the Innocor system. The RT level was found by the strongest breakpoint in the VE/PETCO2-time relationship using SegReg software. Then, tests were applied at constant work rates on different days to estimate the CP. Validity analyses were performed to test the relationships of all threshold indicators with each other. Results showed a high correlation and concordance between RT (328±35.5 W; 4.23±0.39 L·min−1) and RCP (324±34.3 W; 4.21±0.45 L·min−1) power outputs and the VO2 responses of each (p>0.05; t= 1.19; r>0.96; estimated standard error % <5). However, both power outputs corresponded to RT and RCP were approximately 10% higher than the CP (298±32 W) (p<0.001). Our study revealed that the strongest breakpoint in the VE/PETCO2-time relationship in well-trained cyclists demonstrated the RCP with great success, but failed to determine the CP directly.

Anahtar Kelimeler

• Change Point Detection
• Gas Exchange Threshold
• Ramp Test
• Respiratory Compensation Point

Solunumsal Yanıtlara Dayalı Yeni Bir Eşik Belirleme Yöntemi Olarak Respirasyon Eşiği ve Kritik Gücü Göstermedeki Başarısı

Öz

Yeni bir solunumsal eşik türü olarak ortaya atılan respirasyon eşiği (RE) kademeli bir rampa testinde dakika ventilasyonu bölü ekspirasyon sonu CO2 kısmi basıncı (VE/PETCO2) değerindeki zamana bağlı değişimlerin analizine dayanır. Ancak RE tekniğinin yaygın olarak kullanılan önemli bir eşik belirleme yöntemi olan kritik gücü (KG) hangi düzeyde işaret edebildiğine odaklanan bir araştırma bulgusu rapor edilmemiştir. Bu çalışmanın amacı, RE tekniği kullanılarak elde edilen egzersiz şiddetinin, KG’yi hangi düzeyde karşılayabildiğini araştırmaktır. Çalışmaya iyi antrene on erkek bisiklet sporcusu katılmıştır. Sporcuların gaz değişim eşiği (GDE), solunumsal kompanzasyon noktası (SKN) ve RE düzeyleri kademeli rampa testleriyle belirlenmiştir. Bu testlerde GDE ve SKN düzeyleri, Innocor sistemi yoluyla VCO2-VO2 ve VE-VCO2 ilişkilerinde saptanan kırılmalar tespit edilerek değerlendirilmiştir. RE düzeyi SegReg paket programı kullanılarak VE/PETCO2-zaman ilişkisindeki en güçlü kırılma noktası tespit edilerek bulunmuştur. Sonrasında KG’yi hesaplamak için farklı günlerde sabit iş oranlarında testler uygulanmıştır. Tüm eşik göstergelerinin birbirleriyle ilişkilerinin sınanması için geçerlik analizleri yapılmıştır. Bulgular, RE (328±35,5 W; 4,23±0,39 L·dk−1) ile SKN (324±34,3 W; 4,21±0,45 L·dk−1) güç çıktıları ve her birine ait VO2 yanıtları arasında yüksek bir ilişki ve uyum olduğunu göstermiştir (p>0,05; t= 1,19; r>0,96; % tahmini standart hata <5). Ancak hem RE hem de SKN güç çıktıları KG'den (298±32 W) yaklaşık %10 daha yüksek bulunmuştur (p<0,001). Çalışmamız, iyi antrene bisikletçilerde VE/PETCO2-zaman ilişkisinde oluşan en güçlü kırılmanın çok büyük bir başarı ile SKN’yi gösterdiğini, fakat KG’yi doğrudan belirlemede başarısız olduğunu ortaya koymuştur.

Anahtar Kelimeler

• Değişim Noktası Tespiti
• Gaz Değişim Eşiği
• Rampa Test
• Solunumsal Kompanzasyon Noktası

Kaynakça

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