Abstract
Resistance exercise plays a critical role in promoting musculoskeletal health, enhancing cognitive function, and improving mood, making it a cornerstone of physical activity guidelines. This thesis adopts an integrative approach to assess the effects of a new progressively intermittent blood flow restriction (i-BFR) modality during low-load resistance exercise (30% of one-repetition maximum [1RM]) on perceptual responses, mood, cognitive function, and acute physiological markers related to muscle protein synthesis.The research was systematically structured, beginning with two meta-analyses—one on chronic adaptations and one on acute physiological and perceptual responses. Meta-analysis 1 was conducted to address methodological inconsistencies in the literature, such as variations in BFR pressure protocols, training duration, and participant populations. Meta-analysis 2 aimed to investigate the underlying physiological and perceptual responses to BFR compared to HL-RE. Although several mechanisms underlying BFR training have been proposed, they remain under investigation. Due to a lack of long term studies on physiological and perceptual responses to BFR versus HL-RT in healthy adults, the second meta-analysis focused on acute studies.
Specifically, Meta-analysis 1 demonstrated that BFR resistance training (BFR-RT) produces comparable increases in muscle mass and strength to HL-RT, particularly when applied to the lower body for at least eight weeks using personalised arterial occlusion pressure (AOP). While supporting the efficacy of BFR-RT under specific conditions—namely, sufficient training duration and standardised pressure application using AOP—these findings also highlighted the need to better understand its underlying physiological mechanisms and to evaluate perceptual responses and tolerability across different BFR modalities, such as continuous and intermittent application. Meta-analysis 2 showed that BFR resistance exercise (BFR-RE) elicited similar increases in growth hormone (GH) and cortisol compared to HL-RE, but lower responses in insulin-like growth factor-1 (IGF-1) and lactate. Data on other markers (i.e. protein signalling) were limited, so the analysis focused on more consistently reported outcomes. It also revealed that intermittent BFR-RE was associated with lower ratings of perceived exertion (RPE) than HL-RE, whereas continuous BFR-RE produced similar RPE to HL-RE. These findings suggest that BFR-RE - particularly i- BFR, which remains less studied – may offer a viable, lower-exertion alternative to HL-RE, warranting further investigation into its acute physiological mechanisms compared to traditional c-BFR.
Building on these insights, the pilot study introduced a novel i-BFR protocol, consisting of progressively increased pressure throughout the sets. The findings demonstrated that this protocol was significantly more tolerable than c-BFR, with lower RPE and pain (p ≤ 0.05), and resulted in improvements in mood and cognitive function as measured by the Stroop test (p ≤ 0.05). These results highlight the potential of the new i-BFR protocol as a more tolerable and cognitively beneficial alternative to traditional BFR methods.
Following the pilot, Acute Studies 1 and 2 expanded the acute investigation of this novel i-BFR protocol on mood, cognition, and hormonal responses to resistance exercise. Study 1 focused on perceptual responses, mood, cognition, and brain-derived neurotrophic factor (BDNF), revealing that i BFR was perceived as more tolerable based on semi-structured interviews, with BDNF levels showing similar increases 5’ post-exercise across all three experimental conditions (p ≤ 0.05). Acute Study 2 assessed metabolic responses, revealing marked increases in GH concentrations for both i-BFR and c BFR (182% and 734%, respectively; p ≤ 0.05), while IGF-1 only increased significantly in HL-RE (5%, p ≤ 0.05).
In conclusion, this thesis confirms that i-BFR could be a feasible alternative to c-BFR and HL-RE, offering similar acute physiological responses with better tolerability and potential cognitive benefits. These metabolic responses suggest promising mechanisms that may support long-term muscle growth,
but further research is needed to confirm this. Future research should also explore the long-term efficacy of i-BFR and its implications for cognitive and musculoskeletal health
| Date of Award | Jul 2025 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Ifigeneia Giannopoulou (Supervisor) & Neil Maxwell (Supervisor) |